How to Erase Files from a Macintosh Hard Drive

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Permanent Eraser

How to Use Permanent Eraser

Secure Empty Trash

How to Use Secure Empty Trash


IT Help Center
Last Updated December 16, 2008
Copyright © 2005 University of Delaware

How to Erase Files from a Macintosh Hard Drive


The application you use to permanently erase files from a Macintosh hard drive will depend on the version of the operating system running on the computer.

When a file is deleted from a computer, the file's name and location are deleted from the disk's directory. However, the file itself remains intact until the space it occupies on the hard drive is written over by data from another file.

Operating System Application or Utility
Versions OS X 10.0.x–10.2.x Permanent Eraser
Version OS X 10.3.x Permanent Eraser or Secure Empty Trash
Version OS X 10.4.x Secure Empty Trash

Permanent Eraser

If your Macintosh is running OS X 10.3.x or below, you can securely erase files using Permanent Eraser software available from Softpedia. Permanent Eraser will overwrite—up to 35 times—all files you move to the Trash on your Macintosh. The data will be securely removed and no longer readable through traditional means.

NOTE
You cannot recover the files after Permanent Eraser has erased them.


How to Download Permanent Eraser

  1. Link to Softpedia's Permanent Eraser web site. The web page should look similar to the following:

  1. Click the Download button to download the application. (You may need to unstuff the downloaded file using StuffIt Expander.)
  2. After the file is unstuffed, move the Permanent Eraser folder into the Applications folder on your hard drive.

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How to Use Permanent Eraser

NOTE
You cannot recover the files after Permanent Eraser has erased them.

  1. Move the files you want to permanently erase on your computer to the Trash.

  1. Double-click the Permanent Eraser icon to launch the application.  

Permanent Eraser will begin deleting files from the Trash. A window will appear showing you the progress of the application.  

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Secure Empty Trash

Secure Empty Trash is a command built into OS X 10.3 and 10.4. You do not need to download any additional applications. When you use this command, it deletes all traces of files from your hard drive, preventing them from being recovered by anyone.

NOTE
You cannot recover the files after the Secure Empty Trash utility has erased them.


How to Use Secure Empty Trash

  1. Move the files you want to permanently erase on your computer to the Trash.
  2. From the Finder menu, click Secure Empty Trash. You should see a dialog box that looks similar to the following:

  1. Click OK if you want to continue with the deletion(s).

NOTE
If you have only used Empty Trash (not Secure Empty Trash) to delete files before, free disk space will still be on your hard drive. To erase all free disk space, and thereby remove all traces of files that you deleted previously using the Empty Trash feature, you should use the Macintosh Disk Utility feature (located in the Applications folder) to remove this space as follows:

  • Open the Applications folder as you normally do.
  • Click the Utilities Folder.
  • Double-click Disk Utility. You should see a screen that looks similar to the following:

  • From the left-hand column, click the disk, volume, or image from which you want to erase free space. You should see a screen that looks similar to the following:

  • Click the Erase tab.

  • Click the Erase Free Space button. You should see a screen that looks similar to the following:

  • Click the radio button in front of the 7-Pass Erase of Deleted Files option.
  • Click the Erase Free Space button.

If you see a system message that says you are running out of disk space, you can ignore it. When the utility is complete, your hard drive will have the same amount of free disk space available as before you ran the utility.

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