How to revert to an older version of macOS

No, you really don't.

It's probably easier and wiser to simply work through any problems you are experiencing than trying to downgrade your macOS.

Downgrading your macOS to an earlier version is not a task to be taken lightly. It requires that you completely erase the data from your drive, reformat that drive, download and reinstall the older OS and finally recover your files from a backup made prior to your installation of the macOS Tahoe. 

Even then, the Mac’s firmware may have been updated, adding a potential for conflicts and a possible need for DFU mode and a Configurator revive/restore, which requires using another Mac connected to yours. 

If all that sounds complicated and risky, then you understand the reality.

Before you attempt this, cross your fingers, kiss the St. Christopher and hope all goes well on your journey.

1) Back up your Mac with Time Machine (or other backup solution) to an external disk drive.

2) Download the previous OS and create a bootable USB installer for it on a USB flash drive. You can get old versions of macOS here.  Test and make sure it is fit for use after you create it.  If it boots your Mac and launches the macOS installer, then it’s good. Quit the installer then continue to the next step.  Optionally, a previous version may be available on an Intel-based Mac if you use Shift-Option-Command-R startup key combination during startup. You may be offered the macOS that came with your Mac, or the closest version still available

3) Boot your computer in macOS recovery mode and launch Disk Utility. Erase and format the drive in preparation of reinstalling the previous OS. This step will erase all of your stored data.

4) Reinstall macOS on your computer using your prepared USB bootable installer that you  created.

bena327 wrote:

As for as the apple shop i went to is is not possible to down grade from Tahoe to Ventura

I tried myself to revert but could not down load a version of Ventura, I contacted apple support and they tried to help but then said it was best i went to an apple store to see them.

I went to the store and they hummed quite a bit and then said the best way was to replace the whole main board, and hope it comes with the old version of the os, but it might come with tahoe. they said there was no way with an M2 chipset to reinstall older versions as you could not boot from a different device. I also asked if I could have a copy of ventura but they said they did not have them.

Disagree with this statement " As for as the apple shop i went to is is not possible to down grade from Tahoe to Ventura "

What they maybe doing.

Is trying to Avoid the possibility of " the Mac’s firmware may have been updated, adding a potential for conflicts and a possible need for DFU mode and a Configurator revive/restore, which requires using another Mac connected to yours " as my colleague @ D. I. Johnson rightly mentioned

Firmware Compatibility and Secure Enclave Risks

Be aware that upgrading to macOS 26 (Tahoe) likely includes a firmware update affecting the logic board and Secure Enclave Processor (SEP).

Downgrading to an earlier version (e.g., Sequoia) may introduce firmware mismatch issues, leading to instability or loss of functionality.

There have been at least three documented cases where downgrading from Tahoe to an older version of macOS resulted in Secure Enclave malfunctions, requiring full system restoration or hardware servicing.

If you really follow all the instructions from @ D. I. Johnson

You will see there is a way to downgrade and they have provided the Detailed Instructions

Steps 2, 3 and 4 to be exact for their above posting

The last point being although downgrading is possible

Downgrading is not supported by Apple and by most of use

There are too many Risk Factors involved

Proceed at your Own Risk

bena327 wrote:

i want to remove tahoe and go back to an old version of macos

Why? And from your responses it seems you probably aren’t capable of doing it yourself anyway. Deal with any issues you are experiencing and learn how to troubleshoot.

bena327 wrote:

I tried myself to revert but could not down load a version of Ventura

Funny, I found Ventura in the App Store. Search on “macOS Ventura” and it pops right up.

https://apps.apple.com/us/story/id1784326336

And of course to downgrade you have to completely erase your current installation and start from scratch. If you don't have any backups of your data you’ll lose it all, permanently.

I tried myself to revert but could not down load a version of Ventura,

Any other details you can provide that would indicate why your couldn't download Ventura? Any messages?

Were you running Ventura on that Mac before Tahoe?