code: def remove_member(self, member, api=None):
          
          api = api or self._API
          username = Transform.to_member(member)
  
          api.delete(
              url=self._URL['member'].format(
                  id=self.id,
                  username=username
              )
          )
docs: Remove member from a dataset
          :param member: Member username
          :param api: Api instance
          :return: None