Requirements
Your ability to end a listing early depends on the amount of time remaining in the listing and whether the listing has received any bids.
If there are 12 hours or more before the end of the listing, you can end the listing early without restrictions. If there are any bids on your item when you end the listing, you'll be asked whether you want to cancel the bids or sell the item to the high bidder.
If there are 12 hours or less before the end of the listing, your ability to end the listing early depends on whether there are any bids on the item and whether the item has a reserve price.
Number of bids on the item
Can the listing be ended early?
No bids, including no canceled bids
Yes, as long as there aren't any canceled bids.
1 or more bids
Yes, but you must sell the item to the high bidder.
1 or more bids, but the item's reserve price wasn't met
No