If there is less than 12 hours to go and it has bids you can not remove it.
If there is more than 12 hours or the item has no bids then to the right of the item in your active list is a drop down, from the drop down select end item and go from there.
If you are concerned that an item will sell for less than you want then NEVER list with a start bid any less than you will be happy to sell for if it only gets the one bid.
