docs: def remove_root(self, id_):
          """Removes a root node.
  
          arg:    id (osid.id.Id): the ``Id`` of the node
          raise:  NotFound - ``id`` was not found or not in hierarchy
          raise:  NullArgument - ``id`` is ``null``
          raise:  OperationFailed - unable to complete request
          raise:  PermissionDenied - authorization failure
          *compliance: mandatory -- This method must be implemented.*
  
          """
          result = self._rls.get_relationships_by_genus_type_for_peers(self._phantom_root_id, id_, self._relationship_type)
          if not bool(result.available()):
              raise errors.NotFound()
          self._ras.delete_relationship(result.get_next_relationship().get_id())
          self._adopt_orphans(id_)