diff --git a/src/corelib/itemmodels/qabstractitemmodel.cpp b/src/corelib/itemmodels/qabstractitemmodel.cpp
index 95bfb109eb..5c6cc7b587 100644
--- a/src/corelib/itemmodels/qabstractitemmodel.cpp
+++ b/src/corelib/itemmodels/qabstractitemmodel.cpp
@@ -410,26 +410,6 @@ QModelIndex QPersistentModelIndex::sibling(int row, int column) const
     return QModelIndex();
 }
 
-#if QT_DEPRECATED_SINCE(5, 8)
-/*!
-    \obsolete
-
-    Use QAbstractItemModel::index() instead.
-
-    Returns the child of the model index that is stored in the given \a row
-    and \a column.
-
-    \sa parent(), sibling()
-*/
-
-QModelIndex QPersistentModelIndex::child(int row, int column) const
-{
-    if (d)
-        return d->index.model()->index(row, column, d->index);
-    return QModelIndex();
-}
-#endif
-
 /*!
     Returns the data for the given \a role for the item referred to by the
     index.
@@ -517,8 +497,7 @@ Q_GLOBAL_STATIC(QEmptyItemModel, qEmptyModel)
 
 
 QAbstractItemModelPrivate::QAbstractItemModelPrivate()
-    : QObjectPrivate(),
-      supportedDragActions(-1)
+    : QObjectPrivate()
 {
 }
 
@@ -1148,22 +1127,6 @@ void QAbstractItemModel::resetInternalData()
     \since 5.11
 */
 
-/*!
-    \fn QModelIndex QModelIndex::child(int row, int column) const
-
-    \obsolete
-
-    Use QAbstractItemModel::index() instead.
-
-    Returns the child of the model index that is stored in the given \a row and
-    \a column.
-
-    \note This function does not work for an invalid model index which is often
-    used as the root index.
-
-    \sa parent(), sibling()
-*/
-
 /*!
     \fn QVariant QModelIndex::data(int role) const
 
@@ -1885,7 +1848,6 @@ bool QAbstractItemModel::setData(const QModelIndex &index, const QVariant &value
     return false;
 }
 
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 /*!
     \since 6.0
     Removes the data stored in all the roles for the given \a index.
@@ -1900,7 +1862,6 @@ bool QAbstractItemModel::clearItemData(const QModelIndex &index)
     Q_UNUSED(index);
     return false;
 }
-#endif
 
 /*!
     \fn QVariant QAbstractItemModel::data(const QModelIndex &index, int role) const = 0
@@ -2107,33 +2068,9 @@ Qt::DropActions QAbstractItemModel::supportedDropActions() const
 */
 Qt::DropActions QAbstractItemModel::supportedDragActions() const
 {
-    Q_D(const QAbstractItemModel);
-    if (int(d->supportedDragActions) != -1)
-        return d->supportedDragActions;
     return supportedDropActions();
 }
 
-/*!
-    \internal
- */
-void QAbstractItemModel::doSetSupportedDragActions(Qt::DropActions actions)
-{
-    Q_D(QAbstractItemModel);
-    d->supportedDragActions = actions;
-}
-
-/*!
-    \since 4.2
-    \obsolete
-    \fn void QAbstractItemModel::setSupportedDragActions(Qt::DropActions actions)
-
-    This function is obsolete. Reimplement supportedDragActions() instead.
-
-    Sets the supported drag \a actions for the items in the model.
-
-    \sa supportedDragActions(), {Using drag and drop with item views}
-*/
-
 /*!
     \note The base class implementation of this function does nothing and
     returns \c{false}.
@@ -3232,28 +3169,6 @@ void QAbstractItemModel::endMoveColumns()
     emit columnsMoved(adjustedSource, removeChange.first, removeChange.last, adjustedDestination, insertChange.first, QPrivateSignal());
 }
 
-/*!
-    \fn void QAbstractItemModel::reset()
-    \obsolete
-
-    Resets the model to its original state in any attached views.
-
-    This function emits the signals modelAboutToBeReset() and modelReset().
-
-    \note Use beginResetModel() and endResetModel() instead whenever possible.
-    Use this method only if there is no way to call beginResetModel() before invalidating the model.
-    Otherwise it could lead to unexpected behaviour, especially when used with proxy models.
-
-    For example, in this code both signals modelAboutToBeReset() and modelReset()
-    are emitted \e after the data changes:
-
-    \snippet code/src_corelib_kernel_qabstractitemmodel.cpp 10
-
-    Instead you should use:
-
-    \snippet code/src_corelib_kernel_qabstractitemmodel.cpp 11
-*/
-
 /*!
     Begins a model reset operation.
 
@@ -3297,11 +3212,7 @@ void QAbstractItemModel::endResetModel()
 {
     Q_D(QAbstractItemModel);
     d->invalidatePersistentIndexes();
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     resetInternalData();
-#else
-    QMetaObject::invokeMethod(this, "resetInternalData");
-#endif
     emit modelReset(QPrivateSignal());
 }
 
diff --git a/src/corelib/itemmodels/qabstractitemmodel.h b/src/corelib/itemmodels/qabstractitemmodel.h
index ff413c7542..ddebf835c8 100644
--- a/src/corelib/itemmodels/qabstractitemmodel.h
+++ b/src/corelib/itemmodels/qabstractitemmodel.h
@@ -68,9 +68,6 @@ public:
     inline QModelIndex sibling(int row, int column) const;
     inline QModelIndex siblingAtColumn(int column) const;
     inline QModelIndex siblingAtRow(int row) const;
-#if QT_DEPRECATED_SINCE(5, 8)
-    QT_DEPRECATED_X("Use QAbstractItemModel::index") inline QModelIndex child(int row, int column) const;
-#endif
     inline QVariant data(int role = Qt::DisplayRole) const;
     inline Qt::ItemFlags flags() const;
     Q_DECL_CONSTEXPR inline const QAbstractItemModel *model() const noexcept { return m; }
@@ -134,9 +131,6 @@ public:
     quintptr internalId() const;
     QModelIndex parent() const;
     QModelIndex sibling(int row, int column) const;
-#if QT_DEPRECATED_SINCE(5, 8)
-    QT_DEPRECATED_X("Use QAbstractItemModel::index") QModelIndex child(int row, int column) const;
-#endif
     QVariant data(int role = Qt::DisplayRole) const;
     Qt::ItemFlags flags() const;
     const QAbstractItemModel *model() const;
@@ -199,9 +193,7 @@ public:
 
     virtual QMap<int, QVariant> itemData(const QModelIndex &index) const;
     virtual bool setItemData(const QModelIndex &index, const QMap<int, QVariant> &roles);
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     virtual bool clearItemData(const QModelIndex &index);
-#endif
 
     virtual QStringList mimeTypes() const;
     virtual QMimeData *mimeData(const QModelIndexList &indexes) const;
@@ -210,12 +202,7 @@ public:
     virtual bool dropMimeData(const QMimeData *data, Qt::DropAction action,
                               int row, int column, const QModelIndex &parent);
     virtual Qt::DropActions supportedDropActions() const;
-
     virtual Qt::DropActions supportedDragActions() const;
-#if QT_DEPRECATED_SINCE(5, 0)
-    QT_DEPRECATED void setSupportedDragActions(Qt::DropActions actions)
-    { doSetSupportedDragActions(actions); }
-#endif
 
     virtual bool insertRows(int row, int count, const QModelIndex &parent = QModelIndex());
     virtual bool insertColumns(int column, int count, const QModelIndex &parent = QModelIndex());
@@ -301,10 +288,7 @@ public Q_SLOTS:
     virtual void revert();
 
 protected Q_SLOTS:
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
-    virtual
-#endif
-    void resetInternalData();
+    virtual void resetInternalData();
 
 protected:
     QAbstractItemModel(QAbstractItemModelPrivate &dd, QObject *parent = nullptr);
@@ -333,15 +317,6 @@ protected:
     bool beginMoveColumns(const QModelIndex &sourceParent, int sourceFirst, int sourceLast, const QModelIndex &destinationParent, int destinationColumn);
     void endMoveColumns();
 
-
-#if QT_DEPRECATED_SINCE(5,0)
-    QT_DEPRECATED void reset()
-    {
-        beginResetModel();
-        endResetModel();
-    }
-#endif
-
     void beginResetModel();
     void endResetModel();
 
@@ -350,8 +325,6 @@ protected:
     QModelIndexList persistentIndexList() const;
 
 private:
-    void doSetSupportedDragActions(Qt::DropActions actions);
-
     Q_DECLARE_PRIVATE(QAbstractItemModel)
     Q_DISABLE_COPY(QAbstractItemModel)
 };
@@ -444,11 +417,6 @@ inline QModelIndex QModelIndex::siblingAtColumn(int acolumn) const
 inline QModelIndex QModelIndex::siblingAtRow(int arow) const
 { return m ? (r == arow) ? *this : m->sibling(arow, c, *this) : QModelIndex(); }
 
-#if QT_DEPRECATED_SINCE(5, 8)
-inline QModelIndex QModelIndex::child(int arow, int acolumn) const
-{ return m ? m->index(arow, acolumn, *this) : QModelIndex(); }
-#endif
-
 inline QVariant QModelIndex::data(int arole) const
 { return m ? m->data(*this, arole) : QVariant(); }
 
diff --git a/src/corelib/itemmodels/qabstractitemmodel_p.h b/src/corelib/itemmodels/qabstractitemmodel_p.h
index e7d68ef3c4..fca5f76200 100644
--- a/src/corelib/itemmodels/qabstractitemmodel_p.h
+++ b/src/corelib/itemmodels/qabstractitemmodel_p.h
@@ -147,8 +147,6 @@ public:
         void insertMultiAtEnd(const QModelIndex& key, QPersistentModelIndexData *data);
     } persistent;
 
-    Qt::DropActions supportedDragActions;
-
     static const QHash<int,QByteArray> &defaultRoleNames();
     static bool isVariantLessThan(const QVariant &left, const QVariant &right,
                                   Qt::CaseSensitivity cs = Qt::CaseSensitive, bool isLocaleAware = false);
diff --git a/src/corelib/itemmodels/qabstractproxymodel.cpp b/src/corelib/itemmodels/qabstractproxymodel.cpp
index 90b2d1f6bf..e5d8c68e72 100644
--- a/src/corelib/itemmodels/qabstractproxymodel.cpp
+++ b/src/corelib/itemmodels/qabstractproxymodel.cpp
@@ -303,7 +303,6 @@ bool QAbstractProxyModel::setHeaderData(int section, Qt::Orientation orientation
     return d->model->setHeaderData(sourceSection, orientation, value, role);
 }
 
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
 /*!
     \reimp
     \since 6.0
@@ -313,7 +312,6 @@ bool QAbstractProxyModel::clearItemData(const QModelIndex &index)
     Q_D(QAbstractProxyModel);
     return d->model->clearItemData(mapToSource(index));
 }
-#endif
 
 /*!
     \reimp
diff --git a/src/corelib/itemmodels/qabstractproxymodel.h b/src/corelib/itemmodels/qabstractproxymodel.h
index 8eef0551ca..ef4feb5564 100644
--- a/src/corelib/itemmodels/qabstractproxymodel.h
+++ b/src/corelib/itemmodels/qabstractproxymodel.h
@@ -78,9 +78,7 @@ public:
     bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) override;
     bool setItemData(const QModelIndex& index, const QMap<int, QVariant> &roles) override;
     bool setHeaderData(int section, Qt::Orientation orientation, const QVariant &value, int role = Qt::EditRole) override;
-#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
     bool clearItemData(const QModelIndex &index) override;
-#endif
 
     QModelIndex buddy(const QModelIndex &index) const override;
     bool canFetchMore(const QModelIndex &parent) const override;
diff --git a/src/gui/itemmodels/qstandarditemmodel.cpp b/src/gui/itemmodels/qstandarditemmodel.cpp
index d40e5d7923..7192126f91 100644
--- a/src/gui/itemmodels/qstandarditemmodel.cpp
+++ b/src/gui/itemmodels/qstandarditemmodel.cpp
@@ -2850,14 +2850,6 @@ bool QStandardItemModel::hasChildren(const QModelIndex &parent) const
     return item ? item->hasChildren() : false;
 }
 
-/*!
-  \reimp
-*/
-QModelIndex QStandardItemModel::sibling(int row, int column, const QModelIndex &idx) const
-{
-    return QAbstractItemModel::sibling(row, column, idx);
-}
-
 /*!
   \reimp
 */
diff --git a/src/gui/itemmodels/qstandarditemmodel.h b/src/gui/itemmodels/qstandarditemmodel.h
index 34747fa86b..f7d8ffd51a 100644
--- a/src/gui/itemmodels/qstandarditemmodel.h
+++ b/src/gui/itemmodels/qstandarditemmodel.h
@@ -329,8 +329,6 @@ public:
     int rowCount(const QModelIndex &parent = QModelIndex()) const override;
     int columnCount(const QModelIndex &parent = QModelIndex()) const override;
     bool hasChildren(const QModelIndex &parent = QModelIndex()) const override;
-    // Qt 6: Remove
-    QModelIndex sibling(int row, int column, const QModelIndex &idx) const override;
 
     QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
     bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) override;