There’s no way to delete your account.
From their FAQ:
Can I delete my account?
Yes, but not at the moment. This is coming very soon.
LOL! Anyway, try to post an account removal request in the help group: http://www.grouprecipes.com/group/help-group/1678
URLS:
http://www.grouprecipes.com
Please note that AccountKiller.com is not associated with the business listed on this page. AccountKiller provides easy-to-understand instructions and guides on how to cancel charges and relationships from the list of businesses on our site, we have no affiliation with these businesses.