Downgrading macOS

You can't downgrade macOS in place. The only way to do a downgrade is with a clean install. That is, installing onto an erased disk.

Obviously if you erase your current Sonoma startup drive, you'll erase any data on it as well. You would need to make backups of your data BEFORE doing the downgrade, and restore data from backups AFTERWARDS. Even then, you might find that Sonoma had made changes to things like Photos / Music / TV libraries – changes which Monterey did not understand. (I don't know that there will have been such changes in this case, but Apple does change the formats of photo and media libraries from time to time.)

Another possibility might be to install Monterey on a different drive from the Sonoma beta.

Here's the process: Create a bootable installer for macOS - Apple Support

The bootable flash drive is used to install a fresh OS after erasing the drive. Erasing removes everything.

The first release of Sonoma is scheduled to be in 11 days. I suggest you just wait and get the release version.

Of course if you're confident you can perform the evolution and have good backups, you can remove Somoma now and replace it with whatever OS is appropriate.

It will allow you to open Utilities, erase the drive and install a fresh OS. Notice again, the erase part.

You have your answer. What remains is for you to take the bold step to erase and install like you took the bold step to install a Beta OS version.

In Disk Utility, partition your hard drive. In the new partition (container disk) click '+' to install a volume, name it 'Monterey'.

If you have a backup of your Monterey software, clone or copy or restore it to the Monterey volume. If it's an intel Mac, you could use Carbon Copy Cloner for this. Not sure about Silicon Macs.

If Intel, reboot your computer holding the Option key, and choose the Monterey volume. Then, when future Sonoma updates get good reviews, you can run from your Sonoma volume instead.

Mac users have been able to have multiple Operating Systems (System Folders) on a Mac since the year 2000 or earlier. I do so all the time - with OS 9.2 (which I still use on a 2002 Apple G4), and Intel Macs until, perhaps, those with a T2 chip. You select the Operating System for operating the computer at System Preferences (settings)>Startup Disk. T2 Macs and Silicon Macs inhibit your ability to run earlier OS on your computer. I believe that Apple got this idea when Hackintoshes were proliferating.

You should always have your Data in a separate volume from your software. That way, you can run one OS or the other but your data in unaffected.

Backup data restart your mac and click Shift Option Command R on bootup and you will se macOS Monteray Ventura or older (NOTE this does not work on 2023 macbooks

my macbook and the ventura OS is an absolute abomination. most unreliable, buggy, unstable device i have ever worked on.