I think the best advice is to cut it off- likely starting in the pin area. Alternatively, drilling out the pin if you can.
However, for one, I'm not nearly as concerned as others with gentle force. The bearing isn't designed for it, but it isn't "not designed" for it either.
I know I've used the wrong length shaft before and under certain conditions (ie top link sucked in, blower riding up on snow) the shaft can push in with incredible force. I know I'm not alone in this, nor using partially seized shafts because they sat on the bush hog for years. Don't get me wrong, neither of these are good things to do, but I imagine they've happened to at least half the owners, or their employees. I think avoiding excessive force like tying it to a tree and driving away is important, but I wouldn't be scared just because you hit it with a hammer.