Downgrading early 2015 MacBook Air back to its original OS

[early 2015 MB A]

I have an early 2015 MacBook Air with 80 GB of storage available.

I recently upgraded the operating system to macOS Monterey.

I would like to go back to the original operating system that the computer came with.

Can this be done simply ?

 

[Trees]

The first link has some information. The second link is found at the first link page bottom. The second link appears to have information for what you would like to do.

I have not attempted a downgrade, so no way to comment on if a downgrade would be an error free process. Backups are highly recommended before downgrading.

If you don't mind sharing, is there a reason why you would like to revert back to the original OS?

https://support.apple.com/en-us/HT204904
https://support.apple.com/en-us/HT211683

 

[early 2015 MB A]

Hi Trees
Sorry for the delay.

First, to answer your question.

Since upgrading my early 2015 MacBook Air to macOS Monterey it takes much longer to turn on, it is slower, some software doesn't work, and the touchpad doesn't work as well.

I have always been happy with the MacBook Air in the past, so I am planning to use the SHIFT + OPTION + COMMAND + R (Internet Recovery) method to re-install the original macOS that it came with. (Thankyou for the links that explained that to me.)

Now my question.

I would be very grateful if you (or anyone who is reading this) could direct me to any resources that give a description of the do's and don'ts of how to safely erase the disk in preparation for re-installation of the original macOS.

(Just to recap (what I think are) the relevant points.

early 2015 MacBook Air
Intel chip
I think it shipped with OS Yosemite
Currently running OS Monterey

I am planning on using the SHIFT + OPTION + COMMAND + R (Internet Recovery) method to -

1. erase the disk
2. re-install the original macOS that it came with)

 

[Up_And_Away]

If you haven’t already, I’d suggest also posting your question on the Apple Support Community.
https://discussions.apple.com/community/mac_os

Friendly advice, it’s an Apple user based community where assisting someone is voluntary. Imho the best assistance request posts are: 1-here is my setup (specific device, specific OS), 2, I need/want to do A and B. Try to be succinct. If you have other questions I’d suggest waiting until someone responds then do the follow up post. And if they are helpful be very sure to click helpful.
I don’t have sufficient Mac knowledge so I don’t participate in that particular forum. But from what I have seen, there are definitely some experienced and helpful people there.

 

[EdwinG]

early 2015 MacBook Air
Intel chip
I think it shipped with OS Yosemite
Currently running OS Monterey
1. erase the disk
2. re-install the original macOS that it came with)

(Quote snipped for length)

My recommendations:

1. Make a backup of everything on the device
2. Take a note of all the software and licences you have. Once you reinstall, you won't be able to retrieve them easily - most should be in your backups, but not everything (e.g.: TI n-Spire CX CAS Student Edition, I'm looking at you!).
3. Did you do a backup? Good. Now, make a second one! - You're never too careful!

When you restore the original macOS version, expect some software, features and websites to not work as you expect them. There are major changes in macOS that will not be available in earlier versions, including to software developers and webmasters.

As a matter of fact, Microsoft 365 apps (formerly Microsoft Office) no longer supports anything earlier than macOS Catalina (10.15). And that's very common.

Before installing macOS onto your drive, make sure you erase all volumes on the drive in Disk Utility. This will wipe everything clean on the drive, including all your data. Remember that second backup, yeah, that's why you always should have multiple of those.

 

[doogald]

One more thing: before you erase the old device, go into the Music app and do Accounts menu / Authorizations / Deauthorize this device. You're only allowed five computer authorizations with an iTunes Store account. It is possible to deauthorize all devices globally from your account and then re-authorize, but this is a lot cleaner.