Hi, and welcome on this forum.
We (moderators) are not admin, and can't delete your account. As it is not completely registered, it is not even visible. I don't know how Simple Machines Forum works on this, but probably after a few days, the account creation request will be automatically deleted.
Anyway, if your provider blocks emails from VSTEP, even if your old account was deleted, it would not be a good idea to change for your comcast email. You still would not be able to receive emails.
To my mind, the best solution would be that you create an external email account, like on google mail, which is a great tool, totally free : http://www.gmail.com. Let me add that, an email account linked with an ISP is not a good idea, as you are not sure you'll keep the same provider all your life, while you can keep an external and independant webmail email even if you change your provider.
The problem you mention isn't the responsability of VSTEP, it's the responsability of your provider.
Hope this helps !
regards,
Denis