Please note that all your data will be deleted, and there absolutely, no recovery from that. Once your account is scheduled for deletion, it's gone for good. We repeat - we cannot restore any accounts that have queued for deletion..
To delete your account, you must first be logged into the account you want to delete and then go to http://untappd.com/account and scroll down to the bottom of the page and click "Delete Account":
After you click this link, a modal will pop-up. Simply enter your password to delete your account.