Was installing the El Capitan on your Mac a big mistake? Have you had a change of heart and want to go back to Yosemite? Here's how to revert back to Yosemite from El Capitan

Here's what you can't do:

You can’t boot your Mac into Recovery mode and revert to Yosemite because this method can only be used for reinstalling the system that’s currently on the Mac, which in this case is El Capitan.

You can't run the Yosemite installer within El Capitan, because the Mac always wants to have the latest version of OS X.

What you can do is completely erase El Capitan, re-install Yosemite, from scratch and then restore your original pre-El Capitan data from a Time Machine back up you made before you downloaded El Capitan.

Before you start, make a back up of any new files you’d recently added in El Capitan and store them on a hard drive (not the one you are about to use to create the installer though). Don't make a Time Machine back up either - the only Time Machine back up should be your back up of Yosemite before you updated to El Capitan. [Here's how to install the El Capitan article in which we recommend you make a backup first!]

Read: OS X El Capitan vs Yosemite | OS X El Capitan release date | How to download and install El Capitan | How to get on the OS X 10.11 El Capitan public beta |The best new features in OS X El Capitan |Mac OS X El Capitan preview, first look at what to expect from OS X 10.11 | Get El Capitan features in Yosemite

How to create a Yosemite install drive

Before you remove El Capitan from your Mac create a Yosemite installation drive. Here’s how:

Download Yosemite from Purchases

  1. First, download the Yosemite installer from the App Store. It should be in your Purchases section.
  2. Click on the Download button.
  3. After the installer downloads it will auto-launch, and inform you that you're runnign a newer version of OS X. You’ll need to quit the installer at this point as you won’t be able to install it on top of El Capitan.

At this stage you need to create a bootable installer on a separate hard drive. You’ll need at least 8GB of storage available on an external drive, that is formatted with a GUID Partition Table, on which to put the installer. It is important (for this tutorial) to leave the default name, which is Untitled.

Erase Disk OS X

It’s not just a case of copying the download file over though, you should make a bootable OS X Yosemite install drive. Using a bootable installer drive is necessary because you need to erase the drive on your Mac (including all traces of El Capitan) before installing Yosemite. This way you can do a clean install of the OS and restore any data you have in your backup.

There are a few ways in which you can create that installer. You can use the installer’s built-in createinstallmedia tool; use Disk Utility; or perform the Disk Utility procedure using Terminal.

The createinstallmedia method is the simplest, and doesn’t require you to be competent in Terminal – even the Disk Utility method requires a couple Terminal commands. However, you will need to open up Terminal to use it.

Here’s what you need to do to use createinstallmedia:

  1. Connect your Mac to the properly formatted 8GB hard drive. Rename the drive Untitled. (Make sure there is no data on the drive as it is going to be erased!)
  2. Make sure the Yosemite installer (Install OS X Yosemite.app) is in the correct location in the main Applications folder.
  3. Launch Terminal and paste in this command:
  4. sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction
  5. Enter your admin password when required

You will see the progress in the Terminal window, it could take half an hour. Eventually you will see the words: Copy Complete. Done.

Use createimagemedia

You now have your bootable Yosemite install drive ready to recover your Mac from the grip of El Capitan.

Read next: How to maximise, minimise, open, close and zoom windows in Mac OS X

How to remove El Capitan from your Mac

Using Disk Utility to format Mac hard drive

Now you have your Bootable Installer, and have backed up any new files, you can safely erase the El Capitan volume. You have to erase it before you can install Yosemite again.

Here is how to boot from that Bootable Installer and wipe El Capitan from your Mac:

  1. Shut down your Mac and connect the drive to your Mac. Hold down the Option/Alt key at startup and when you see the drive icon labeled Install OS X Yosemite, click on the arrow below it to start the install.
  2. Select Disk Utility when the OS X Utilities window appears.
  3. When the Disk Utility app launches, choose your Mac’s hard drive and click on the Erase tab. Name your hard drive and select one of the OS X Extended formats.
  4. Click Erase and wipe your hard drive.

How to install Yosemite from a Bootable Installer

Installing OS X Yosemite

Once your Mac has been wiped you can install the Yosemite from your Bootable Installer. Here’s how:

  1. Quit Disk Utility.
  2. Select Install OS X, click Continue, and follow the installation process.
  3. Assuming you made that back up before you installed El Capitan you can now connect to your Time Machine drive and run Migration Assistant to restore all your files from the back up.
  4. Finally any additional data you had created since installing El Capitan, and had backed up (not using Time Machine) can be restored.

Read next: Features in OS X 10.12, successor to El Capitan: Wishlist