With the rash of so many other sites, TopicSpotter has been sold and has claimed all the articles for its own, with no way to delete them. Your only hope is to file a DMCA Notice of Infringement and pray for the best.
Unfortunately, writing for article platforms is currently the Wild West, and there is no way to stop the sale of these sites. However, be warned if you buy one of these revenue-producing sites: if the site claims all its articles are by the site owner, be wary and do your research; get the advice of a lawyer on intellectual property rights. You don't want to end up with Federal Trade Commission Complaints, or be sued by authors.
Your best bet is to head over to the Wayback Machine at http://www.archive.org and look for the Terms and Conditions of the site you are thinking of buying. If there is a revenue split, in all likelihood the authors own their respective articles.
If you buy such a site, be aware that you will have to continue to either honor the original Terms and Conditions, or give authors a chance to remove their content (90 days is about right). Make sure you send an email notice to each author's registered email address.