Opening Revit central file from ProjectWise, when Revit opens, user gets an error that R: (this can be any letter) is already mapped and Revit cannot open the file.
None of the Net Use commands on the command line would release it. The Windows Explorer didn't always show it, but if it did the option to remove it is greyed out. The user had to reboot between Revit sessions.
From the command line use the command: SUBST /D [Drive Letter:] In this case the drive letter was R: