code: def clear_mask(self):
          
          if self.masktag:
              try:
                  self.canvas.delete_object_by_tag(self.masktag, redraw=False)
              except Exception:
                  pass
  
          if self.maskhltag:
              try:
                  self.canvas.delete_object_by_tag(self.maskhltag, redraw=False)
              except Exception:
                  pass
  
          self.treeview.clear()  # Clear table too
          self.fitsimage.redraw()
docs: Clear mask from image.
          This does not clear loaded masks from memory.