WebPopupMenu.DeleteAllRows
From Xojo Documentation
Method
Deletes all the rows of the PopupMenu.
Notes
You will often want to delete all rows before loading any rows so that you do not end up with duplicates.
Examples
Delete all the rows from the popup menu and then adds new rows:
PopupMenu1.DeleteAllRows
PopupMenu1.AddRow("One")
PopupMenu2.AddRow("Two")
PopupMenu1.AddRow("One")
PopupMenu2.AddRow("Two")