code: def unregister(self):
          
          pdu = RegisterForeignDevice(0)
          pdu.pduDestination = self.bbmdAddress
  
          # send it downstream
          self.request(pdu)
  
          # change the status to unregistered
          self.registrationStatus = -2
  
          # clear the BBMD address and time-to-live
          self.bbmdAddress = None
          self.bbmdTimeToLive = None
docs: Drop the registration with a BBMD.