Can I delete giveaways after they are finished?

1) points not return also if delete giveaway after it end,only return if u can delete before it end.
2) winner must agree delete
3) if winner agree to delete you can send msg to support ticket for ask delete by provide proof image or make the winner comment in your giveaway that him agree delete (but points not return also if delete in this way,only return if delete before giveaway end).
4) You can create giveaway then in description you write you are not sure keys will work because very old and you wold be happy if who enter will allow you to delete the giveaway in case keys not work,gentle asking it,but is not possible to "Force" or "ask" to people to delete the giveaway for example you can say "Please i would be happy if who enter let me delete the giveaway in case key not work" but you can't say "if you enter this giveaway you must\agree to delete"
Because the decision is up to the winner not up to the creator of the giveaway.

There are at least two groups with the rule that if the key turns out to be not working you will agree to delete the giveaway.
So you might want to join them and do your giveaways for this groups.

Groups in question: (First link = SG Page / Second Link = Steam Page, for the groups.)
https://www.steamgifts.com/discussion/O5LX8/group-delete-giveaway-if-key-is-not-working
https://steamcommunity.com/groups/dgikinw

https://www.steamgifts.com/discussion/rSWOI/lootboy-codes-for-coinsdiamonds
https://steamcommunity.com/groups/lootboy_sg