How do you remove wiper arm on 1997 firebird?

I have a 99 and one of my wipers broke off when i opened the hood while a wiper was folded. oops. fold over plastic boot to remove 13mm nut. if the arm does not pry off with hand pressure...you will need to borrow a puller from auto store. also a battery terminal puller works. after cleaning wiper grooves on car..add a little anti sieze b4 putting new wiper arm...