Beta won't update past 1.11.0.7

Several weeks ago, an error in updating the store caused the 1.11.0.7 Beta to be downloaded to all Xbox One devices, whether or not the player had joined the Beta program. It caused quite a stir in the Xbox community, but apparently you missed it. The problem was corrected within a day, but unfortunately, the Store app does not support automatically updating to a previous version, so reinstating the 1.10 release requires manually uninstalling the game and reinstalling it. (Be sure you've got backups of any worlds you want to save, because uninstalling will delete them!)

Even more unfortunately, any world that was opened while the Beta was installed will have been upgraded to the later version and will no longer be available to play in 1.10. If you have a backup of the 1.10 world you can restore that and continue playing it. Otherwise, I'm afraid you won't be able to play such worlds until the 1.11 release comes out.

Alternatively, you could join the Beta, as you were wondering. You should not lose your old worlds when you do this, but keep in mind that the Beta is a test version and should be assumed to have bugs, possibly including bugs that can corrupt your world. You will be warned of this when you join the Beta; don't skip reading the information. And again, if you change your mind and leave the Beta, any worlds you opened while using it will be unavailable in 1.10 but you'll be able to open them when 1.11 comes out (assuming they aren't corrupted).

I am closing this report as Invalid because it does not describe a bug (in the game). If you have further questions or problems getting your Xbox back to 1.10, please contact Xbox Support.