My son moved from his bedroom 4 months ago and recently a beeping sound ( every 3 minutes or so ) goes off from the ceiling light bulb fixture in hid room. Looked everywhere in room for a gismo that he left behind but nothing beeping was found except for ceiling fixture. There is no other detectors close. Should I disconnect light bulb fixture from ceiling ?

Lights don't beep. It is a smoke or CO detector or some other device indicating a low battery.

you could try the process of elimination as you suggest....disconnect things until the beeping stops. (first, check the smoke or CO detectors as recommended)