def METHOD_NAME(self):
    if self._slit_overlay_mark is not None:
        image_figure = self.app.get_viewer(
            self._default_image_viewer_reference_name
        ).figure
        # We need to do the following instead of just removing directly on
        # the marks otherwise traitlets doesn't register a change in the
        # marks.
        image_figure.marks.remove(self._slit_overlay_mark)
        image_figure.send_state('marks')
        self._slit_overlay_mark = None