code: def delete_marker(self, iid):
          
          if iid == tk.ALL:
              for iid in self.markers.keys():
                  self.delete_marker(iid)
              return
          options = self._markers[iid]
          rectangle_id, text_id = options["rectangle_id"], options["text_id"]
          del self._canvas_markers[rectangle_id]
          del self._canvas_markers[text_id]
          del self._markers[iid]
          self._timeline.delete(rectangle_id, text_id)
docs: Delete a marker from the TimeLine
  
          :param iid: marker identifier
          :type iid: str