How to uninstall the Windows10 preview system?

Since Microsoft introduced the win10 system, many users can't wait to install win10 on their own computers, but this is a new operating system, and there are many places that people can't adapt, so many users are installing and using them. After I found out that I still like the original system, what should I do? Friends who want to uninstall win10 system can come and find out!

If you are running Windows8, and you are using this preview version installed by ISO, 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 do not have recovery media, you can create a USB recovery drive.
If you are running Windows XP, Windows Vista or Windows 7, you will not be able to 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 Windows 10 Preview. Only when the final version is released, upgrade it to Windows, 10 official version, which means that Windows 10 system can not be uninstalled, only Can be replaced by another system by reloading.