So, on the same drive as I have Trainz I have an old Windows installation taking up 23GB of space. I cannot delete it because I require permission from the ironically named Trustedinstaller . I've watched 2 videos , paused at each step and did exactly what they said and it won't budge. I've tried disabling Windows Module Something or other, no luck. Any suggestions short of formatting the drive ? I will not rest until I beat this thing.