I assume you took the nut off already. Your almost had it. Spray some liquid wrench (a bunch)on the shaft, let it sit for an hour or so. Get a BIGGER HAMMER, about a 3 pound short handle sledge works fine, there are usually 2 size pickleforks, you need the smaller. Dont be afraid to hit it, usually need 6-7 good hits once it is seated and it will pop right off.