'Remove QoS rules from port.
:param port: port object.
:param qos_policy: the QoS policy to be removed from port.'

def delete(self, port, qos_policy=None):

    if (qos_policy is None):
        for rule_type in self.SUPPORTED_RULES:
            self._handle_rule_delete(port, rule_type)
            if self._rule_type_has_ingress_direction(rule_type):
                self._handle_rule_delete(port, rule_type, ingress=True)
    else:
        for rule in self._iterate_rules(qos_policy.rules):
            self._handle_rule_delete(port, rule.rule_type, ingress=self._rule_is_ingress_direction(rule))
