Try restarting computer to relase any locks / kill any hung processes
ALSO: delete the folder C:\Users\Administrator\AppData\Roaming\npm\node_modules\windows-build-tools (or at least delete the file/folder C:\Users\Administrator\AppData\Roaming\npm\node_modules.windows-build-tools.DELETE)
ALSO: make sure you run the installation command in an elevated command prompt (right click cmd, run as administrator)
Lastly, it can take a loooooong time (30mins plus) - wait it out.