The copy of OS X that is included with your Mac is not considered a retail purchase, so unfortunately you will be able to access it only through Apple's installer. However, this requires you to purchase a separate license of OS X. One easy option (which I have discussed before) is to purchase OS X from the App Store, then create a boot drive from its contents. Granted, the use of Time Machine makes restoring from backup relatively easy, but if for some reason you need to repartition the hard drive or install a new one on your system, you will first need to install OS X again. While convenient for those with fast broadband connections, sometimes you may find yourself in a location without fast Internet and would benefit from having a way to reinstall OS X from scratch. Instead, if you wish to reinstall OS X you simply reboot to the OS X Recovery HD and use the tools there to format your hard drive (should you choose to), then run the installer to download OS X from Apple's servers.

You can now quit Terminal and eject the volume.Since its move to online purchasing and distribution of its operating system software, Apple has no longer included gray recovery DVDs with its Mac systems.

When Terminal says that it's done, the volume will have the same name as the installer you downloaded, such as Install macOS Monterey.

After the volume is erased, you may see an alert that Terminal would like to access files on a removable volume.

Terminal shows the progress as the volume is erased.

When prompted, type Y to confirm that you want to erase the volume, then press Return.

Terminal doesn't show any characters as you type.

When prompted, type your administrator password.

If the volume has a different name, replace MyVolume in the command with the name of your volume. Each command assumes that the installer is in your Applications folder, and MyVolume is the name of the USB flash drive or other volume you're using.

Type or paste one of the commands below into Terminal, then press Return to enter the command.Open Terminal, which is in the Utilities folder of your Applications folder.Plug in the USB flash drive or other volume that you're using for the bootable installer.

Macbook air boot usb stick