The most complete way to uninstall FS One is to use the uninstall program within the control panel and after that delete the FS One directory.

To do this with Windows 2000/XP
Go to Start-Control Panel-Add/Remove Programs, find FS One and remove it. After the computer is done removing the program find and delete the FS One directory (this is usually located at C:\Program Files.)

To do this with Windows Vista
Go to Start-Control Panel-Programs and Features, find FS One and remove it. After the computer is done removing the program find and delete the FS One directory (this is usually located at C:\Program Files.)
Note: for Vista users it would be a good idea to turn off the UAC before doing this see http://www.fsone.com/Support/tm.aspx?m=143