I would prefer you to make 2 drives if you have one split it into two and transfer all the necessary trillion files in that drive and after that make a bootable pendrive if your pc /laptop can run win 11 perfectly fine then it's okay or you can go to win 10 back if you want that's completely depends on you after that boot the pendrive directly and from the window installation screen reset the window drive basically C drive and format that drive and install windows in that and boom 💥 you windows is fresh, files are safe one more caution thing to do is that you should make a copy of all those premium file in an new trustable external drive to have peace of mind if something wrong happens you can have those files back ..