'Detach a network_interface from an instance.
:param server: The :class:`Server` (or its ID) to detach from.
:param port_id: The port to detach.
:returns: An instance of novaclient.base.TupleWithMeta'

def interface_detach(self, server, port_id):

    return self._delete(('/servers/%s/os-interface/%s' % (base.getid(server), port_id)))
