When windows10 came out I did like so many other people an upgrade from windows 8.1 to windows 10. Unfortunately I didn't make a clean installation and just simply did an update. I find that I still have a lot of junk on my computer that I am no longer using from windows 8.1 and I think it's making my computer sluggish. I would like to format my computer and make a clean installation but I can't find the windows 10 product key. Can anyone help?