If Disk Cleanup is not working properly and does not remove Windows Update ... it with the DISM tool Run Cloud Reset Use Storage Sense or alternative free junk cleaner software.
New Snapdragon laptops can now do clean installs of Windows 11, but your idea of "clean" may differ from what you get. Thanks ...
Normally, you need a Microsoft account to use Windows 11. You can bypass that — and more — with a freely available script utility.