Just a quick update on this for anyone that comes across this problem like we did today:
This method is confirmed to work. (Check that you disable/stop all running Ranger services in step 1, we found at least 1 additional RM service that stopped us from deleting the Ranger files)
Local Administrator Logon.
1. Open Computer Management. Go to the services section, find Ranger Network and Ranger Security Monitor and disable them both (Security Monitor first).
2. Delete the Ranger folder from c:\program files and delete the Rngrupdt directory from the root of the c:\.
3. Open registry editor. Go to HKEY_LOCAL_MACHINE\SOFTWARE\Hyperion Security Software and delete this key.
4. Still in registry editor. Go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon and find the value 'shell' and change the value from 'rgrshsub.exe' to 'explorer.exe'
5. In the same key find the value 'Userinit' and change the value from 'rgrunit.exe' to 'userinit.exe'
6. Reboot the machine.