You cannot delete your account.
Try to contact them via http://www.hattrick.org/Help/Contact.aspx?InfoInstanceID=4 and tell us your results.
URLS:
http://hattrick.org
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.