We could not find any method for deleting our test account. Besides, search engines give quite some complaints by other people not being able to. In that case the answer is mostly a common on: (1) contact them ( firstname.lastname@example.org ) and request deletion of your account and related content. (2) If that doesn’t work, you may choose to anonymise your data when logged in.
You may also want to contact the company providing this site: email@example.com and request opting out and/or deletion of your data. Further, see the PP about data retention and so on: http://www.ebaumsworld.com/pages/privacy