If your item has a bid on it and with only 8 hours to go then you will not be able to take if off your listing. All you can do is cancel the bid that you already have and just hope and pray that nobody makes a last minute bid. You will need to keep your eye on the auction and cancel bids if they come in. If you do get a last minute bid and are unable to cancel it, you are going to have to hope that the buyer is understanding. It is a pain, because things do get broken, but with less than 12 hours to go, you cannot take it off your listings. Hopefully if you have left a note on it that should help....but not all buyers actually read messages - that is a big problem.
The problem you may have is if somebody does bid on it at the last minute and you tell them it is lost/broken - they may well think that you didnt get enough money for it and are backing out - it does happen unfortunately. If that happens and you get a neg then come back to the boards for further advice. I always say, if in doubt ask on the boards first before making decisions that may well be the wrong decision.
Good luck to you though. As a seller myself I understand your side of things
Remember - it takes 17 muscles to smile and 44 muscles to frown - SO KEEP SMILING 🙂