If you can get the other side undone then it will remove the tension on the offending cup and you should be able to tap the shredded one round with a hammer and punch.
If not get a small set of mole grips, insert the jaws into the axle hole and wind out the adjuster till it grips then undo.
If it is still stuck consider cutting a couple of opposing notches in the cup and jam a piece of steel strip or such in to use as an extractor.
If you can get the other side undone then it will remove the tension on the offending cup and you should be able to tap the shredded one round with a hammer and punch.
If not get a small set of mole grips, insert the jaws into the axle hole and wind out the adjuster till it grips then undo.
If it is still stuck consider cutting a couple of opposing notches in the cup and jam a piece of steel strip or such in to use as an extractor.
Good luck.
T..d.. p..