Problem: Corrupted user accounts and how to remove a user via the Registry

Answer: Have you restarted the Daemon from the Services Applet panel? If so, and the problem still persists, please do the following:

If the configuration for Titan/Cornerstone has been stored in the Registry, you may have a corrupted user entry in your Registry. Close down the Admin console. If you can, stop the service; if not, you may still continue. 

Launch the Registry, browse HKLM, locate the South River Technologies folder, select Titan FTP Server, select Servers, browse each folder labeled with a number (you can search on ServerName on the right-hand side to find your FTP server), and expand to see the Users section (you can search for Username to find the User on the right-hand side). The users will be assigned a random numbered folder. Browse to you locate the user's folder and rename that folder to folderold. Go back to the console and try removing the user.