def METHOD_NAME(self, MAC):
    '''
    unregister a DAC device from the server
    Input:
        MAC address
    Output:
        none
    '''
    MACkey = self._MAC(MAC)
    self._updateLock.acquire(blocking = True)
    if(self._queues.has_key(MACkey)):
        logging.info(__name__ + ' : unregistering device %s.'%MAC)
        self._queues.pop(MACkey)
    self._updateLock.release()