You can delete a giveaway at any time before it ends.
Once it ends, you'll need the winner's permission to delete the giveaway- this is best done by having them leave a comment in the giveaway itself stating they approve of the deletion (otherwise, you'll need to provide a screenshot of the agreement). Without this, it's unlikely you'll be able to get a deletion.
As far as wait time goes, support appears to have been mostly inactive during the holidays. There are currently roughly 2500 pending support requests, not including user reports (which are typically addressed only after other tickets are cleared). As such, there may be a bit of a wait before your ticket will be able to be looked at. Tickets are addressed in the order they were submitted, so it's just a matter of them getting to it. Just be careful not to "bump" your ticket, as that will cause it to reset its queue time to the new comment- meaning all other currently active tickets will then be pushed ahead of yours in the response order.
Comment has been collapsed.
30 Comments - Last post 5 minutes ago by drschnell
43 Comments - Last post 17 minutes ago by adam1224
67 Comments - Last post 36 minutes ago by hallak65
46,874 Comments - Last post 1 hour ago by adambiser
119 Comments - Last post 2 hours ago by Celtic69
2,156 Comments - Last post 2 hours ago by Milesprower11
69 Comments - Last post 3 hours ago by MikeWithAnI
235 Comments - Last post 11 minutes ago by Utamy
40 Comments - Last post 30 minutes ago by Mitsukuni
27 Comments - Last post 35 minutes ago by FranckCastle
69 Comments - Last post 48 minutes ago by Gekkonidae
209 Comments - Last post 50 minutes ago by erintesden
918 Comments - Last post 53 minutes ago by erintesden
28 Comments - Last post 53 minutes ago by yannbz
Comment has been collapsed.