cleanmgr.exe is the built-in Windows utility. It is a legacy tool that has existed for decades, designed to help users free up hard drive space by deleting temporary, cached, and unnecessary files.
Via Command Line: While there isn't a dedicated flag for "extended mode" in the standard help list, running the /sageset command as an Administrator usually reveals the system file options (like "Previous Windows Installation(s)") that are hidden in the standard user view. cleanmgr.exe
– leaves many "safe but stale" files that other cleaners remove cleanmgr