Your buyer was supposed to click on 'buy it now' and not pay until they had been to inspect the item and make sure it was satisfactory.
It's looking like you did an 'off ebay' deal which, if ebay get wind of, you will get your account sanctioned as they will see it as themselves being denied their fees.
To end your listing go to your seller hub 'selling' and click on the 'Other actions' down arrow. End my listing.
