How can I revert to windows 7?
What are you planning on doing there? Anything that you can do there can be done exactly the same way in W8. The only reason you would be using the "Modern UI Fullscreen" UX with apps would be that you were trying to use MUF apps. You can't use those in W7, so if you want to simulate a W7 UX in W8, just don't use any MUF apps. Further if you are so against the MUF UX that you can't adjust to having a (Fullscreen) Start Screen instead of a Start Menu you can get any of a number of third-party replacements for that remaining difference.