Just moved into this apartment
ADEMCO 6150ADT keeps going off. Have no code. Kept beeping. Set off alarm and keeps reseting itself and every time I open door it goes off. ADT will not give me code and apartmanager does not know it. Can I disconnect?

1.Tell the manager to fix the thing immediately.

2. Call alarm company and have it fixed and send the bill to the manager.

If you have a key to the panel, disconnect the power feed line and remove the battery. Some units are supplied by a plug in power adapter, usually screwed to the outlet. Remove the screw and pull the power supply and battery. Otherwise, do as Talinaman says.