I have tvOS 11.3 beta installed and I’d like to install the regular, default current version so that my aTV is both stable and continues to update itself. How can I do this and can I avoid wiping the device first?
Turn off beta software updates in the updates menu in settings. Then wait for the next public release and you'll be updated to that.
This is the only way to do it without attaching the AppleTV via USB to a iTunes for a complete restore.