It depends on what you wish to achieve. It just can't be that the program is not installed, but the disk is there. If the disk is present after a reboot, that means the RAM Disk drivers are installed and running. If you want to entirely remove the application, my advice would be as follows.
1) Delete the following registry keys:
HKLM\System\CurrentControlSet\Services\vvramd
HKLM\System\CurrentControlSet\Services\SPVDPort
HKLM\System\CurrentControlSet\Services\SPVVEngine
On Windows 10, you may need to reboot at this point. Otherwise the .sys files at the next step may be locked by the system and you may not be able to delete them.
2) Delete the following files in the %SystemRoot%\System32\Drivers directory:
spvdbus.sys
spvve.sys
3) Delete the entire installation directory in %PROGRAMFILES%\SoftPerfect RAM Disk.
4) Make sure you don't have
spvdbus.sys and
spvve.sys in any other folder.
5) Reboot.