Passing None as a widget to QTreeWidget.setItemWidget() will do what the user expects, remove the widget from the item. Just like QTreeWdiget.removeItemWidget()

But this is not accepted by typing stubs.

Example code :

from typing import Optional
from PySide6.QtWidgets import QTreeWidget, QTreeWidgetItem

t = QTreeWidget()
item = QTreeWidgetItem(t, ['abc'])

# it should be possible to remove the item widget for an itemt.setItemWidget(item, 0, None)

Not sure you should fix that one, but it was reported on PySide6-stubs.

Similar issue reported in PYSIDE-3042 but for QListWidget