how do I roll back Sequoia 15.2 to 15.1?

FWIW, Apple Intelligence was included in Sequoia 15.1 as well. So there's no point in downgrading. If you don't want to use AI, don't use it. You can turn it off in System Settings > Apple Intelligence & Siri.

fredfromorange wrote:

Several 3rd party apps stopped working with 15.2. Can I just backup to a 15.1 date? and I don't need or want the AI

One misconception that exists.

That Time Machine backups up both the Operating System as well as the Users' Data

TM Backup Only backups the User Data

It does not have a full and working copy of the Operating System

The only way to downgrade ( not suggested ) would to follow the advise from @Barney-15E

For greater details from another posting from the same Contributor

Substitute the names appearing in that link, appropriately

Downgrade from Sonoma to Ventura / factor… - Apple Community

You create a bootable USB installer from the full installer version you want, boot from the installer, erase the drive, reinstall macOS, then migrate from a backup created before you updated.

william98 wrote:

I just installed this update, but I had no idea I was upgrading from 15.1 to 15.2. All I saw was "improvements" to Pages etc. Not one mention that this was an OS upgrade to 15.2 -- which includes Apple's AI. I had avoided this update precisely because I didn't want AI on my computer, and now I've got it because Apple did not tell me that the updates I was installing were Sequoia 15.2. I don't know whether this was an oversight or deception by Apple, but I want to get rid of it. How do I go back to 15.1?

I would not advise falling back/ or behind in the macOS.

All things change— you do not have to actively pursue AI

The current stable release of Sequoia including bug fixes, security updates is macOS 15.2

Several 3rd party apps stopped working with 15.2. Can I just backup to a 15.1 date? and I don't need or want the AI

Don't understand any of that. Could you please elaborate as to how to proceed?