We get a lot of complaints about this site. You cannot delete your free account, so it seems.
Try to contact them via http://www.fileserve.com/contact-us.php and share your results.
And, it’s always a good idea to read the tip below about anonymising your account.
URLS:
http://fileserve.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.