If there is no bid or if the leading bid is below the reservation price you can cancel the listing on the page Selling - Active . 

If you’ve received a bid, we need your as well as the highest bidders  approval in order to cancel the listing. You can contact the highest bidder by going to the listing and click contact bidder.  
Once you get an approval in our messaging service you can contact customer service to cancel the listing.

We also recommend that you add a note to the listing about your intention on canceling the listing as well as why to avoid further bids.

The fee for add-ons will be charged even if you cancel the listing.