How to uninstall win10 system?

Win10 uninstall tutorials need friends to come to understand, many friends ask Xiaobian win10 how to uninstall, Windows10 preview version of the problem is still quite a lot, if you are not used to how to uninstall it? Please see below.

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 have not recovered 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 Windows 10 Preview, you will not be able to recover from previous Windows versions by using the recovery partition on your computer.
If you are currently using Windows RT, you will not be able to uninstall the Windows 10 preview, and only upgrade the Windows 10 official version when the final version is released.
In other words, the Windows 10 system cannot be uninstalled and can only be replaced by another system by reinstalling.