Delete an activity (run).

        :param id_num: The activity ID to delete

def delete_activity(self, id_num):
        """Delete an activity (run).

        :param id_num: The activity ID to delete


        """
        url = self._build_url('my', 'activities', id_num)
        r = self.session.delete(url)
        r.raise_for_status()
        return r