Well, there isn't. You have to deliver the gift OR accept the "not received" mark on your profile (which will also deduce one GA slot from you).

EDIT: You can, however, blacklist this person so he won't be able to enter any of your future GAs. But you'll still have to deliver the gift or accept the "not received" mark.

as long as you did not send it out am sure you can roll for a new one . you could open a ticket and tell them you dont support cheaters :p

Nope. If they haven't broken any SG rules or already own the game, you won't get a reroll.

it seems you cant do that, but if you suspicious of the guy, write the support to re-roll the ga

I'm afraid you only have 2 options and those are give him the code and don't give him the code but take a not received.

For future giveaways and you don't want that cheaters win them you can use SG tools because it has lots of functionality including this: Your account must never been VAC banned.

You might be able to request a reroll if your selectee has non-activated games or multiple wins of the same game in which they have not yet been temp banned / suspended.

just give the guy his game and blacklist him.
use sgtools to prevent vac-banned people from joining your ga (if you post them in the forums, public ga are unrestricted).

To be really honest: I wouldn't give him the key. You better live up your values then admit to the weakness.

Well you could also talk to him and try to convince him to let you reroll. :P

Pee on him to show dominance!

Another bullshit reason to ask for reroll. He is already VAC banned, don't you think it's stupid to punish him twice for the same thing?

I hate cheaters and such but just to let You know - there have been many cases where people got VAC banned for literally no reason. That's pretty sad but it happens. What is more, Valve does nothing about it. Well, Valve DOES CAN remove the VAC ban but You would have to be very patient and talk with them for quite a while to get what You wanted.

Racism against VAC banned people. Racists. All of you.

You should stick to the commitment you made when you created the GA and gift it to the winner. That person, no matter what their Steam transgression might be, entered your GA in good faith expecting a game if they won. It is unfair of you to hold them accountable for something that is not against the rules of this website.

Now that you know better you can take precautions for your next batch of GAs...in 2017 :P

If you don't want to use SGTools, you can add a warning in the description of your next GAs, something like "Do not enter if you have a VAC ban!"
I used something like that when I was giving away a Franchise pack for Saints Row - I asked not to enter if the participant owns some of the basic games, the first winner ignored it, and the reroll was accepted. You just have to set the conditions first.

Sausage still frozen after cooking, I got a problem with a wiener.
Monkey took my food, I got a problem with a lemur.
Got in a car accident, I got a problem with a broken femur.
palms are sweaty, knees weak, arms are heavy. There's vomit on
his sweater already: mom's spaghetti

Uh, you do understand that VAC is not 100% reliable?
https://www.youtube.com/watch?v=FG6fo34JOAk

We've all had winners that weren't ideal. But if you make a giveaway, you set the rules for people to enter. This guy qualified to enter your GA and won. The right thing to do is give him the gift and if you are picky about who wins your giveaways, become more selective about who enters.