You cannot delete your account.
Please contact them via http://support.iconfinder.com/customer/portal/emails/new?q=delete%20my%20account
In the message body, ask them to delete your account, and supply your account details.
URLS:
http://iconfinder.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.