This instruction goes for all Datanta and Amistarium variants (com, co.uk etc.). The only difference may be that you need to have the wordings in your own language (such as Spanish).
Be logged in on the site. Click Edit profile on the main page. On your left, click Account Settings. Scroll and click the deletion link.
URLS:
http://www.amistarium.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.