Have you tried Windows 10 and are you not satisfied? Although Microsoft claims that its new operating system is the best version of Windows, there may be many who disagree, or who love the good old 7 too much.
If you try Windows 10, with the free upgrade offer, and decide that Windows 7 or 8.1 is better for you, you can go back to your old operating system very easily.
Microsoft allows you to quickly revert back to your favorite operating system in Windows 7 or 8.1, if you don't like Windows 10, directly from your operating system settings.
It should be mentioned that the downgrade uses the Windows.old folder that is automatically created during the installation of Windows 10.
From the Start menu, follow the path: Settings / Updates and Security.
There you will find the recovery option.
From the option shown in the image below, with a single click you will start the downgrade.
Once you click this option, Microsoft will ask you why you want to change operating system. 
It should be noted that the downgrade process takes a while and you will probably lose your installed applications.
All your personal files will be kept as they were.
