If you need to unload CompareDWG for the current user use the AutoCAD command
     CUILOAD
to unload 'FRXC' from your user interface. You can also remove the CompareDWG software directory from the support file search path.
CompareDWG will then remain available for other users/profiles.

To remove CompareDWG completely for all users close all AutoCAD sessions and use the Uninstall option in the Windows start menu or in the Control Panel/ Programs section.