New to this site, have a few Questions about my bird

Hello everyone, I have a mullucun he is 10 yrs old. Recently he has come up with the idea that it is fun to distroy my wall. He has chewed the plaster off the corner down to the metal and on the bottom he has demolished the plastic base board, and then decided it would be fun to rip the the the paint and the paper right down to the drywall. He was doing this when I was sleeping or when I was at work. So now he is locked up at night and while i'm at work, which I feel bad about cuz I am gone for 9 hours out of the day. So now he still does it when I am home but only when I'm not looking, I can't turn my back on him for a second or else hes on the floor continuing to destroy my wall!!! Is there anything I can spray on the wall that will detere him from this behaviour??? He has lots of toys as well so it's not that he's board.