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.datanta.com/
pls delete my acoount from this datanta site my name registered as manoharanm@ yahoo.co.in