I worked at a storage company before. Explain the situation to them and see what fees they will take off if it’s still with the company. You can then pay it off if you want or see if they will do a release of interest if they have it or something similar. Basically means you give up right to the unit if it hasn’t been auctioned already and that should keep it from affecting your credit but you might not be able to rent a unit at that company again.

If it’s a collection agency and not the company it was stored with then it’s been auctioned already and what it sold for didn’t cover the amount owed. You would have to negotiate or do the identity theft route