Most likely the AP is zerotouch provisioned (ZTP) through "aruba activate" or "cloud central", you should see the process when you have a serial cable connect to it. You can also follow the traffic through your firewall and looking for outgoing traffic to (i guess) *.arubanetworks.com
For detach from ZTP you have to contact TAC support.
Or simply block the outgoing connection on your firewall, lol ;)