I've opened a ticket to re-roll, but apparently it is not so simple. And the giveaway can only be deleted if you explicitly give permission to do so. Btw, I've send you a message in steam chat.

Hello djlr.

Region restricted giveaways must be properly tagged as such during giveaway creation. We (the support) cannot reroll this giveaway as the next winner may run into the same region restrictions. In situations like this, the options are one of the following:

1. Giveaway creator gets the winner an unrestricted key that they can activate.
2. The giveaway is marked as "Not Received."
3. The giveaway is deleted, if the winner has agreed to it.

If a giveaway creator wants to delete, they will need the winner's agreement first. Winner is not obligated to give this permission. This is why Vecchia has asked if you'd agree to the deletion. It's up to you if you agree or not.