Creator asked to remove his giveaway.

just consent to the deletion on the giveaway page and creator and mods will take care of it

All you really need to do is leave a comment on the GA page saying that you agree to the deletion of the Giveaway.

• To delete a giveaway, barring special circumstances, consent by both GA creator and winner is required. Note that deletion approval is not required to be provided. While it's generally the respectful, polite thing to do, there may be cases where you believe the GA creator was trolling with his giveaway, and you may not feel a deletion is warranted. Leaving the giveaway open may also encourage the GA creator to provide the key later on.
  
  Further, GA creators often offer "bribes" [read: another steam key, usually a low value one] in exchange for agreeing to the deletion, and you may have the belief a certain giveaway warrants such a response. At the same time, you may not in any way encourage those, due to the site's no solicitation rule, so do be aware of that. Again, the respectful, polite thing to do is to agree to deletions whenever possible, and that's very much something that you'll be appreciative of when it's reciprocated on your giveaways in the future. I very much encourage that approach when possible.
  
  Again, you do not, however, have to agree to the deletion if you do not wish to, and there may be benefits to you if you go down that path. At the same time, however, you're locking yourself out of entering for that same game for the duration, as the GA creator can simply push for a deletion if you win the giveaway elsewhere, and you're setting yourself up for some karmic response from a community that generally views accepting a GA creator's circumstances as the responsible thing to do (when clear intent of misuse isn't shown), and doesn't take well to implied extortion or unwarranted harassment to GA creators (of which you'd be choosing to leave a visible record of).

• To process the deletion, the GA creator puts in a support ticket, including either a link to a screenshot of the winner confirming approval or to a comment on SG by the winner confirming the approval. The preferred method by staff is for winners to comment directly in the giveaway, when possible, so that the comment is easily accessible and verifiable.

• Directly referencing a user in the forums (such as by linking to their giveaway, as you've done in your thread here) for a matter that could be perceived as negative, based on information that is not publically available (eg, any information that is not either their SG or their Steam profiles, available through an official public statement, or present or hinted at by that individual within the same discussion that a comment is being made in reply to) can be considered as "calling out" and can get you a 2 suspension for inappropriate behavior.
  
  This is based on a previous, stricter rule which doesn't seem to be in the guidelines anymore (replaced by "If you notice a user not following our guidelines, do your best to politely explain our rules with relevant links or quotes to our guidelines when appropriate. If they do not take action or deny any wrongdoing, please submit a user report ticket so we can take action if necessary"), but it's a rule that does still seem to be enforced.
  
  As the giveaway in question is not important to the outcome of your question, it'd be best to remove it from your thread, in respect of those expectations.

I suggest you to agree with the deletion. His reason is better than those who unsure if the key of the game that they want to giveaway is working or not. Then, they expect us to agree with the deletion of the giveaway if the key is not working.

As soon as you voice your consent to delete, you're done. The rest is up to the creator and support.