How to uninstall Windows 8.1 and return to the old system Windows 7 without restoring the media disc

Solution:

If Windows 8 is attached to a computer, you can restore it to Windows 8 by initializing the computer. Personal files are not affected, but applications not attached to the computer will need to be reinstalled. For more information, see how to restore, recover, or initialize your computer.

If you are running Windows 7, Windows Vista, or Windows XP, you need to use the recovery or installation media (usually a DVD) attached to your computer to reinstall the previous version of Windows.

If no recovery media exists, you can use the software provided by the computer manufacturer to create a recovery media by using the recovery partition of the computer before the update. For more information, see the support section of the computer manufacturer website. After installing Windows 8.1, you will not be able to use the restored partition on your computer to resume using the previous Windows version.