Canceling a Sale after UID Case opened

[eastearlpickers]

I sold an item, the buyer did not respond until after I opened the UID.  Buyer requesting that I cancel the transaction due to death in the family.  It matters not to me if thats the truth or not, but I'd like to move on and re-list the item ASAP.  The buyer wants it canceled, and I am agreeable to that, do I have to wait for the UID to clear on its own?  Unfortunately, I cannon find how to do it.  In Resolution Center when I open the case, my only option to close it out is to select "Payment Recieved".  How can I cancel at buyer's request?