While a lot of people (mostly windows itself ) like windows 10, many don't want it. If you're one of those that don't want it, you'll definitely want to read this.
Yesterday, windows 10 decided to auto-install itself on my computer, today it decided to do so on my mom's computer aswell. I'm not sure how many other people's computers have had windows 10 auto-installed on them so far, but nonetheless I think that knowing how to uninstall windows 10 or prevent it from auto-installing would be useful for all of you.
First: how to prevent windows 10 from uninstalling. There should be a windows icon near the right side of your taskbar, right click it and select "Go to windows update" on the right there should be a "change settings" button, change the "important updates" thingamajig to say "Check for updates but let me choose whether to download or install them" and congratulations, windows 10 now cannot auto-install on your computer.
Second: How to revert back to your previous operating system after windows 10 has installed itself on your computer. Go to settings > update&security > recovery and look for the "Go back to windows XX" thing (it will say either 7, 8, or 8.1, depending on what your previous OS was) and voila! Your computer is now windows 10-free (P.S.: windows 10 will almost immediately try to reinstall on your computer after you do this, so you'll want to make sure it can't auto-install again as soon as you get back to your previous OS)