Account deletion seems absent, as can also be read on e.g. http://customize.org/groups/topic/13441?highlight=account
You may want to send them a mail asking for deletion: firstname.lastname@example.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.