I have not checked this myself, as sadly I never paid attention. However, if the VTroot folder remains on your system after uninstalling CIS (and this is reproducible every time) then I would tend to classify this as a bug in the uninstaller.
After all, uninstalling a program is supposed to remove all traces of it. Therefore, if this folder is left each time this means there is a problem with the uninstaller. Please file a bug report if this is reproducible.