Adjustable cup used as a fixed cup with ring tack welded to frame? There's a good chance the ring is welded to the cup also. As others have said, remove the crank so we can get a better idea what's going on here. Pull off the cup from the non-drive side while you're at it. Remove the spindle and the balls. This will give you a chance to evaluate the condition of the race on the cup in question and decide whether you want to follow the advice implied by [MENTION=493684]SurferRosa[/MENTION] and just leave the cup in place rather than grinding off tack welds.
Brent