Account deletion is not yet implemented (but it seems they are working on it!). In the mean time, they can do it manually for you.
Go to: http://adf.ly/contact
Choose “Other” test as a subject and ask them to terminate your account.
They will more than happily help you. Note that it can take up to three days for them to respond.
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.