'Delete a QoS policy.
:param context: neutron api request context
:type context: neutron.context.Context
:param policy_id: the id of the QosPolicy to delete
:type policy_id: str uuid
:returns: None'

def delete_policy(self, context, policy_id):

    with db_api.context_manager.writer.using(context):
        policy = policy_object.QosPolicy(context)
        policy.id = policy_id
        policy.delete()
        self.driver_manager.call(qos_consts.DELETE_POLICY_PRECOMMIT, context, policy)
    self.driver_manager.call(qos_consts.DELETE_POLICY, context, policy)
