You can cancel an auction or sale at any time, but you may still be obligated to move forward with the sale.
To end a public auction, click on the "End Auction Early" link on the Auction Details page.
If your reserve price has been met, the buyer who placed the highest bid will be declared the winner.
If your reserve price hasn't been met, the auction will end without a winner.
To end a private sale, click on the "End Sale Early" link on the Sale Details page. The sale will end without a winner.