code: def _remove_rid_from_vrf_list(self, ri):
          
          if ri.ex_gw_port or ri.router.get('gw_port'):
              driver = self.driver_manager.get_driver(ri.id)
              vrf_name = driver._get_vrf_name(ri)
              if self._router_ids_by_vrf.get(vrf_name) and (
                      ri.router['id'] in self._router_ids_by_vrf[vrf_name]):
                  self._router_ids_by_vrf[vrf_name].remove(ri.router['id'])
                  # If this is the last router in a VRF, then we can safely
                  # delete the VRF from the router config (handled by the driver)
                  if not self._router_ids_by_vrf.get(vrf_name):
                      LOG.debug("++ REMOVING VRF %s" % vrf_name)
                      driver._remove_vrf(ri)
                      del self._router_ids_by_vrf[vrf_name]
docs: Remove router ID from a VRF list.
  
          This removes a router from the list of routers that's kept
          in a map, using a VRF ID as the key. If the VRF exists, the
          router is removed from the list if it's present. If the last
          router in the list is removed, then the driver's method to
          remove the VRF is called and the map entry for that
          VRF is deleted.