Reset iMac 2019 to factory

[Applefan2015]

I have bigsur beta on my imac, for some reason it’s not installing beta 2. So I want to factory reset my iMac, and start again.

When I go to reinstall Mac OS which originally shipped with my iMac, it brings up the beta for bigsur.

How do I go about reinstalling the original Mac OS which shipped with my iMac?

Thanks.

Applefan2015

 

[Apple_Robert]

Do you use Time Machine as your backup? If so, go into Time Machine and pick a date before you installed Big Sur. If you don’t have any type of backup, take a look at this article. In the future, install beta on an external drive. It will save you a lot of trouble.

How to downgrade macOS Big Sur to macOS Catalina [Guide]

Want to Downgrade macOS Big Sur Beta to macOS Catalina? Here's how you can downgrade your macOS 11 Beta to macOS 10 without bootable drive.

www.ytechb.com

 

[pldelisle]

Try

sudo softwareupdate --force -i -a

in Terminal.app.

 

[Applefan2015]

Update, I used Shift-Option-⌘-R and successfully reset my iMac to factory.

Thanks for the replies.