Remember, trying out an early
build like this can be risky. That's why we recommend that you don't
install the preview on your primary home or business PC. Unexpected PC
crashes could damage or even delete your files, so you should back up
If you want to stop using Windows 10 Insider Preview
and return to your previous version of Windows, you'll need to
reinstall your previous version from the recovery or installation media
that came with your PC—typically a DVD. If you don't have recovery
media, you might be able to create recovery media from a recovery
partition on your PC using software provided by your PC manufacturer.
You'll need to do this before you upgrade. Check the support section of
your PC manufacturer's website for more info.
After you install Windows 10 Insider Preview, you won’t be able to use the recovery partition on your PC to go back to your previous version of Windows.