Originally Posted by The Fixer
Loosen the crank bolt and ride the bike for a couple of miles. Hopefully the crankarm will work itself loose from the bb spindle.
I've tried this and it works fine. As mentioned, loosen the retaining nut, don't remove it. It didn't take miles. I have a relatively steep driveway, so I put the bike in a low gear and stood on it hard up the drive a few times.