Use the link (webform) to request account deletion. Of course, fill in the email address that is known to be linked to your account name.
Cancelling paid service (NB: no refunds), see http://www.blogtalkradio.com/faq.aspx
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.