For PyQt/PySide. A simple function for clearing the contents of a QTreeWidget/QTreeView, since these classes lack convenient clear() or clearContents() methods. Takes a QTreeWidget or QTreeView object as an argument.

qt_ClearTreeWidget.py

import PySide
from PySide import QtGui

def clearQTreeWidget(tree):
    iterator = QtGui.QTreeWidgetItemIterator(tree, QtGui.QTreeWidgetItemIterator.All)
    while iterator.value():
        iterator.value().takeChildren()
        iterator +=1
    i = tree.topLevelItemCount()
    while i > -1:
        treeWidget.takeTopLevelItem(i)
        i -= 1

For PySide2

from PySide2.QtWidgets import QTreeWidgetItemIterator
def clearQTreeWidget(tree):
    iterator = QTreeWidgetItemIterator(tree, QTreeWidgetItemIterator.All)
    while iterator.value():
        iterator.value().takeChildren()
        iterator += 1
    i = tree.topLevelItemCount()
    while i > -1:
        tree.takeTopLevelItem(i)
        i -= 1