DeleteTaskGroup.
        [Preview API] Delete a task group.
        :param str project: Project ID or project name
        :param str task_group_id: Id of the task group to be deleted.
        :param str comment: Comments to delete.

def delete_task_group(self, project, task_group_id, comment=None):
        """DeleteTaskGroup.
        [Preview API] Delete a task group.
        :param str project: Project ID or project name
        :param str task_group_id: Id of the task group to be deleted.
        :param str comment: Comments to delete.
        """
        route_values = {}
        if project is not None:
            route_values['project'] = self._serialize.url('project', project, 'str')
        if task_group_id is not None:
            route_values['taskGroupId'] = self._serialize.url('task_group_id', task_group_id, 'str')
        query_parameters = {}
        if comment is not None:
            query_parameters['comment'] = self._serialize.query('comment', comment, 'str')
        self._send(http_method='DELETE',
                   location_id='6c08ffbf-dbf1-4f9a-94e5-a1cbd47005e7',
                   version='5.1-preview.1',
                   route_values=route_values,
                   query_parameters=query_parameters)