'Deletes a group.
For a full list of available parameters, please refer to the official
API reference:
https://developer.openstack.org/api-ref/block-storage/v3/#delete-group'

def delete_group(self, group_id, delete_volumes=True):

    post_body = {'delete-volumes': delete_volumes}
    post_body = json.dumps({'delete': post_body})
    (resp, body) = self.post(('groups/%s/action' % group_id), post_body)
    self.expected_success(202, resp.status)
    return rest_client.ResponseBody(resp, body)
