Go back to your previous version of Windows
For a month after you upgrade to Windows 10, you’ll be able to go back to your previous version of Windows from Settings > Update & security > Recovery. This will keep your personal files, but it'll remove apps and drivers installed after the upgrade, as well as any changes you made to settings.
If go back isn't available
If you have a product key for your previous version of Windows, use the media creation tool to create installation media for Windows 8.1 or Windows 7, and use it to do a clean install.