Information in this tutorial applies to macOS Big Sur (11.0) and later.
Older versions of the operating system follow similar steps.
Backing Up Your MacBook Air
Plug in an external storage gadget to your MacBook Air’s port.
Apple
When purchasing anexternal drivefor backup purposes, ensure the drive has enough capacity to cover your internal drive.
OpenSystem Preferenceson your Mac.
Select theChoose Backup DiscorSelect Diskoption.
Choose yourUSB storage deviceand clickUse Disk.
On the next screen, selectSave.
Within a few minutes, the backup process begins.
Your first backup may take a few hours or more depending on how much data is on your machine.
Check back in the Time Machine preference pane to confirm when Time Machine has finished its first backup.
It will note when its latest backup completed.
Apple
For more information, check out our detailedtutorial on using Time Machine.
Sign Out of iCloud on Your MacBook
SelectiCloud.
(In newer versions of macOS, selectApple ID/Apple Account>iCloud.)
(In newer versions of macOS, selectOverview>Sign Out.)
You might be prompted to slide in your password when signing out of iCloud.
When the dialog asks whether you want to keep a copy of your iCloud data, selectKeep a Copy.
If done successfully, the Mac’s software appears as it did when you first unboxed the unit.
Begin by shutting down your Mac from theApplemenu or by pressing thepowerbutton once on your keyboard.
Once your system is completely off, hold down theCommandandRkeys on your MacBook’s keyboard simultaneously.
Without letting go of any previous keys, turn on your MacBook Air by pressing thepowerbutton.
Once you see the Apple logo or a Spinning Globe on screen, you might let go of theCommandandRkeys.
Within themacOS Utilitieswindow, selectReinstall macOS.
ClickContinueto begin the macOS installer.
The macOS installer may ask you to unlock your disk or drop your Mac password before continuing.
Your MacBook will restart several times as it erases the old disk and installs macOS.
A progress bar shows you the estimated amount of time remaining.
Once this is complete, the machine boots to the Setup Assistant to begin setting up the computer.
Allow the computer to start up into Recovery Mode.
Proceed when you see the macOS Utilities window.
In themacOS Utilitieswindow, selectDisk Utility.
Under theViewmenu option, selectShow All Devices.
Below theViewmenu button are the drives attached to your machine.
Select your primary drive; it contains Macintosh HD within it.
Once your drive is selected, selectErase.
In theErasewindow, leave all parameters as is and clickErase.
If successfully erased, your machine will turn on to a flashing question mark in a folder icon.
TheErase All Content and Settingsprocess in System Preferences works like the same-named feature on the iPhone.
