I am giving my MBAir latest model (256 GB flash drive) to a relative. I want to erase my files using Disk Utility. When I go there the options are all greyed out. How do I erase the files and reinstall Mountain Lion which I purchased from the App Store? Thanks.
MacBook Air (13-INCH, MID 2011), Mac OS X (10.7.4)
You cannot erase the startup volume without booting first to another disk. Furthermore, Disk Utility will not erase just your files. It can only erase the entire disk.
Create a new user account for your relative. Log into the new account and delete your account. If you wish to erase and reinstall Mountain Lion do this:
Install or Reinstall Lion/Mountain Lion from Scratch
Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Erase the hard drive:
1. Select Disk Utility from the main menu and click on the Continue button.
2. After DU loads select your startup volume (usually Macintosh HD) from the
left side list. Click on the Erase tab in the DU main window.
3. Set the format type to Mac OS Extended (Journaled.) Optionally, click on
the Security button and set the ZeroData option to one-pass. Click on
the Erase button and wait until the process has completed.
4. Quit DU and return to the main menu.
Reinstall Lion: Select Reinstall Lion/Mountain Lion and click on the Install button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible
because it is three times faster than wireless.
Dick Utility Erase Not Available
