https://www.saotn.org/windows-server-2012-r2-disk-cleanup-dism/

1. Open and elevated command prompt and run:

    dism.exe /online /Cleanup-Image /AnalyzeComponentStore 

   to get info on when the last cleanup was done and other misc info.

2. To perform a basic cleanup run:

    dism.exe /online /Cleanup-Image /StartComponentCleanup