I have -$700 in my PayPal, what can they do if I don’t pay it?

Back in December I sold an item that was obviously real and legit, due to it being a virtual item I was not able to back up my proof against a charge back filed against me (no tracking number or anything), the money that was sent to my account isn't in there anymore and is now -$ 700, I don't see myself ever paying back debt that wasn't my problem, I saw it coming and removed my bank and card before I was CB'ed, will paypal be able to do anything if there's not a linked bank or card? I'm not…

I have -$ 700 in my PayPal, what can they do if I don't pay it?