Surface Pro 3 here, I upgraded from 8.1 to 10. Now I want to give this to my wife and want to completely erase it. When going into recovery I get 3 options: Keep my Files, which I don't want. Remove everything, which I do want. And Restore Factory Settings which I do want, but it denotes it will reinstall win 8.1 which I don't want. So I choose the Remove Everything option. It gives me an error saying "Could not f ind the recovery environment" "Insert your Windows installation or recovery media, and restart your PC with the media." I did try connecting a Win10 recovery USB drive, but haven't tried to reboot into it yet, I suppose that's my next step. It's stupid stuff like this that give iOS/Android users the ability to talk trash about Windows.