How to Secure Erase an External Hard Drive on Mac

So you just got a new external drive and wanted to sell or give away your old one? Or your current external drive just got over-cluttered, and you want to completely wipe it out to regain all the storage space?

erase external drive mac

In this quick guide, you’ll learn two different ways to securely erase an external drive on a Mac computer.

Before you proceed, make sure you’ve already backed up all your important data. Once you use any of the methods below, the drive will be completely erased and all data will be removed permanently.

1. Using Disk Utility

erase drive mac

First off, connect your external hard drive to a Mac. Make sure the device can be detected by the computer. Then follow the step-by-step tutorial below:

  • On your Mac, go to Applications > Utilities > Disk Utility.
  • Click on the Erase tab (next to “First Aid”).
  • Select the disk or volume in the list on the left panel.
  • Choose a file system to which you want to format your external drive.
  • Next, click the Security Options button at the bottom.
  • Here you can specify how securely you want to wipe the drive, move to Most Secure if you are paranoid because this option overwrites more times to the disk space, though the process tends to be slower.
  • After that, click Erase to continue.

Note: If your drive is an SSD, you won’t be able to click “Security Options” as this option will be grayed out. It’s because SSDs don’t have to go through this process due to the way it manages files.

2. Via Terminal (Command Line)

If for any reason, Disk Utility fails to wipe your drive by showing errors like “unable to write to the last block of the device“.

You can try erasing the drive via the Terminal app, though it’s a command-line tool that requires you to be a bit geeky.

  • Search “Terminal” in Spotlight.
  • Open it and enter this line: diskutil list
  • Now you’ll see a list of disks there, target yours through the disk identifier. Jot down the information.
  • Next, type: diskutil eraseDisk JHFS+ (diskname diskidentifier)
  • Press the Enter key and your external drive will be erased completely.

This video also has more:

Final Words

Wiping an external hard drive clean on Mac is an easy task. With one of the above methods, you should be able to get the job done quickly.

If you have any questions during the process, let us know by leaving a comment below.

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    Thanks for your instructions. This is the message I have right now: Started erase on disk2
    Unmounting disk
    Creating the partition map
    waiting for partitions to activate
    [ 0%..10%..20%..30%..40%..50%………..]

    What is the longest time this can take to activate completely, please?

  • Douglas

    Following your Terminal method, It results in this statement: Error: -69760: Unable to write to the last block of the device.
    I have tried many other approaches which all end up with this statement.
    The Drive is a Glyph GPT50-2TB.
    All the Data has been saved x3 and all I need is to erase the drive to enable a reformat, which I have been told from the manufacturers will bring the unit back to full health. currently it starts up and a few seconds later shuts down then a few seconds more lights up (front Blue indicator light) and can be seen by Terminal with diskutil list.
    Any help would be welcome, any specialist applications that could override the message?