To uninstall G6 FTP Server, remove it via the 'Add/Remove Programs' item of the Control Panel or use the shortcut in your start menu. After uninstallation, delete the configuration files (Accounts.ini, Groups.ini and Ftpsrv.ini).The only remaining file is the '_g6uninst.exe' (~20Ko) in your windows directory, you can delete it manually after uninstallation.
That's all.