Updating imac super drive
Once your Mac is running a newer version it won’t allow you to downgrade it that way. In this article we show you how to downgrade mac OS.
Before you start the process of downgrading your Mac make sure you back it up - during the downgrade process you will completely wipe your hard drive, so you would lose any new files you have created since the High Sierra installation (and anything since you last backed up your Mac for that matter, you did back up before you installed High Sierra, didn't you?
If not, skip ahead to Downgrade without a Time Machine backup below. If you don't use Time Machine, clone your startup disk to a spare external drive or at the very least make a copy of any files you've created or modified since you upgraded.
Before we begin, it's important to note that when you restore from a backup, you'll wipe everything on your startup disk. If you've got photos in the Photos app and you don't use i Cloud Library, manually export them to an external disk so you can re-import them later.
Maybe software you use regularly no longer works - if you were using Adobe Illustrator, for example, you may find it no longer works (read about other apps that don't work in High Sierra here).Whatever your reason for hating the new Mac OS, you may be wondering if you can revert back to the older version of the operating system.Unfortunately downgrading to an older version of Mac OS X isn’t as simple as finding the older version of OS X and reinstalling it.) You must also bear in mind that Sierra (or an older version of the Mac OS) will require more space than High Sierra - this is because High Sierra requires less space to operate.The good news is that if you are trying to revert from High Sierra to the version of Mac OS X that shipped on your Mac it should actually be an easy process, thanks to a new feature in mac OS Recovery that has existed since mac OS Sierra 10.12.4.