if both ends of the bolt are missing (i.e. no head and no threads), you can try punching it out. There will probably be too much play in the bushings if the control arm is still on the car, but if you take the control arm off, and set the spacer in the bushing on two hard objects so the spacer doesn't move, but the bolt hole is still clear, there's a good chance you can whack it out with a punch and a hammer.