[Always do backups before such drastic measures.] The best way to install Windows is to go to another Windows box and use the the Window Media Creation Tool to create a bootable USB stick <https://www.microsoft.com/en-ca/software-download/windows11> Alternatively you could download the WIndows 11 Disk Image. During installation, you have to answer a lot of questions. It is extremely hard to evade linking the installation with a global Microsoft account (google to learn the ever-evolving tricks). Good news: Windows can let other partitions on the disk remain. In earlier years, it would just grab the whole disk. Once it is installed, Windows will spend a lot of time installing updates and rebooting. Installing updates is quite slow (perhaps due to anti-malware software). And it lies about whether there are more updates. When it says there are none, ask it to look again. You also need to separately run the Microsoft app store app and ask it to do updates. You also need to run you system vendor's update thingee too for some driver and firmware updates. Even then, it is useful to see what firmware is available on the vendor's web site This whole process involves multipler reboots, each requiring babysitting.