How to Erase All Data From a Mac Computer

by Jedadiah Casey

You can erase all the data from a Mac computer and start over with the Mac OS X installation disc. This is useful to return the computer's software to factory condition and remove any personal files from the system. When erasing the internal hard drive on a Mac, you can choose to perform a low-level multi-pass erase, which decreases the likelihood of any sensitive data being recovered.

Insert the Mac OS X installation disc into the disc drive, then restart the computer.

Press and hold the "C" key until the Mac begins to boot from the disc.

Click the "Next" arrow.

Click the "Utilities" menu at the top of the screen, then click "Disk Utility."

Click the Mac's internal hard drive in the left column of the window.

Click the "Erase" tab.

Click to choose a partition type under "Format." For example, choose "Mac OS Extended (Journaled)." Enter a volume name in the "name" box, as an option.

Click "Security Options," as an option. With this menu, you can choose to write zeroes over the entire disk, to low-level format the disk seven times or to low-level format the disk 35 times. Choosing any of these options makes file recovery on the disk much more difficult.

Click the "Erase" button twice.


  • check An operating system, such as Mac OS X, must be reinstalled on the Mac after performing these steps before the computer can work properly again.


  • close This is a destructive process. Be sure to have a backup of any important data on the Mac before proceeding. Writing zeroes or performing a multi-pass erase takes significantly more time than a quick erase.

About the Author

Jedadiah Casey started writing professionally in 2007, with articles published in "The Flagler Times" newspaper. He has more than 20 years of experience with computers and networking. Casey holds a Bachelor of Science in information systems from the University of Central Florida, as well as professional industry certifications.