I am going to upgrade my front sway bar, but couldn't figure a non-destructive way to get the bushing off/out. I can move the bar over the bushing but can't get the flange away from the bushing.

Who has done this before?

Spray some rust penetrent of the bushing. Pull the flange out as far as it will move and put the bolts through the holes from the back side. This gives room to drive out the bushing. Push the flange against the fender well. Use a small punch and hammer to break the bushing away from the flange. Start at the split into the bushing if you can find it. Pull off the flange and bushing. Remove the bar from the other side with the flange and bushing still on the bar. Easier to remove the other one when off the car.

Thanks. why did I think it would be easy?

You can try warming it with a heat gun and trying on the flange to break loose the bushing. They get stuck pretty good after 40 years.
Bruce