Got a feeling the "backup your mac with Time Machine" step is a good sign of how you'll have to uninstall it.

may the FAQ be with you.

»How do I leave the OS X Beta Seed Program? To leave the program, visit the Leave Program page and follow the instructions to remove your Apple ID and your computers from the OS X Beta Seed Program. This will stop pre-release updates from appearing in the Mac App Store on your computers.« – https://appleseed.apple.com/sp/betaprogram/faq

If you don't already know how to roll back an entire disk image or OS from a backup, you probably shouldn't install the beta.

It won't be that different anyway. You'll get the opportunity to check for resolved bugs, and report new ones. If that doesn't interest you, there's no benefit.

Agreed entirely, but leaving the beta program isn't the same thing as removing the beta.

No, it isn't.

Do an erase and install using OSX Recovery. The built in partition should download a released version of the OS and not a beta version.

It's in the Frequently Asked Questions.