If it's the lower pivot pins, they have a taper into the arms that needs breaking. Un-screw the bolt a few turns and hit it with a hammer to break it free.What machine, and which bushing? Do you mean the lower pivot pin(s)?
Older machines the taper pins are threaded. The newer machines are through bolted. On the older machines remove the grease zerk or the pin can hydro lock in the holeIf it's the lower pivot pins, they have a taper into the arms that needs breaking. Un-screw the bolt a few turns and hit it with a hammer to break it free.