I followed your advice found the returnil folder and deleted it and got my disk space back
Hi gonefishin and others who may have the same question,
The supplemental virtual storage is actually just a very large file with special properties that forces Windows to see it as a new disk when it is opened (IOW, mounted by RVS/RSS). When it is closed (dismounted), the file cannot be opened by other programs and looks like nothing other than a big, empty file depending on the amount of data and/or files you have saved within it while in Virtual Mode.
The name of the file is rvsystem.img and can be found in the Application Data folder that Bruce helped you to see. While deleting the Returnil folder will do the same thing, it is recommended that you delete the file itself in case you plan to reinstall RVS/RSS in the future.
Before you attempt to delete the Virtual Disk file however, make sure you dismount it (close) in the RVS/RSS GUI first.