Use their webform and request deletion. Termination of your account will only be possible if you have no outstanding orders/actions. According to their PP all your data will truly be erased. Now that is clear, the way we like it.
URLS:
http://www.sedo.com/
https://sedo-us1.custhelp.com/app/ask
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.