Windows 8.1 preview can not be uninstalled how to do

Windows 8.1 preview (Preview) can be installed unloaded, Microsoft pointed out in the official Q&A page, Windows 8.1 preview does not support uninstall, you can restore the entire system to the factory state. If your computer comes pre-installed with Windows 8, you can use a computer refresh to restore it to Windows 8. Your personal files will not be affected, but non-PC pre-installed apps will need to be reinstalled, and the Windows 8 app store may no longer provide the apps you installed when using the preview version.

If you are running Windows 8, and you are using this preview version of the ISO installation, you will not be able to uninstall it. You will need to reinstall Windows 8 using the recovery or installation media that came with your computer. If you don't have recovery media, you can create a USB recovery drive.
If you are running Windows XP, Windows Vista or Windows 7, you cannot uninstall this preview version. To revert to the previous operating system, you will need to reinstall from the recovery or installation media (usually DVD media) that came with your computer. If you don't have recovery media, you can use the computer manufacturer's software to create recovery media from your computer's recovery partition before updating. After installing the Windows 8.1 preview, you will not be able to recover to the previous Windows version by using the recovery partition on your computer.
If you are currently using Windows RT, you will not be able to uninstall the Windows RT 8.1 preview. Only upgrade to the official version of Windows RT 8.1 when the final version is released.