Disable car alarm

My 2008 Prius has started sounding its alarm after the hybrid battery was rebuilt. It goes off at irregular intervals. I thought that simply leaving it unlocked might help as the anti-theft alarm wouldn't have been set, but that doesn't help.

I just want a cheap cure to entirely and completely disable the alarm forever. Can anybody tell me what wires to cut? If not, will pulling the fuse for the horn out do the job?

Much obliged.