3 Ways to Securely Wipe an External Hard Drive Clean on Mac

Last updated: Jun. 9, 2017

You've just got a new SSD (solid-state drive), and wanted to sell or donate the old HDD (hard disk drive)? Or your current external drive just got over-cluttered, and you want to give it a complete wipe to regain all the space.

Either way, in this article we're going to show you three different ways to securely erase an external drive on a Mac computer (iMac, MacBook, etc.).

Note: the guide below works with all types of external disks, it doesn't matter whether you are using an HDD, SSD or a flash drive. Though SSDs can be a bit different when you use Apple's built-in tools. We'll explain later.

Warning: 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 clean, and all data will be removed permanently. You've been warned.

1. Use Stellar Drive Wipe

Stellar Wipe Mac is a powerful third-party Mac app that's designed to securely erase a file/folder or the entire drive. To wipe an external drive, open the software and select "Drive Wipe" option. Next, select your drive, choose a wiping algorithm that you want (read the description first) and start the erasing process. Compared to the other two options, this method is much easier and quicker.

2. Erase via Disk Utility

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

  1. On your Mac, go to Applications > Utilities >Disk Utility.
  2. Click on the "Erase" tab (next to "First Aid").
  3. Select the disk or volume in the list on the left panel.
  4. Choose a file system to which you want to format your external drive. E.g. for a flash drive, it's usually FAT32.
  5. Next, click the "Security Options" button at the bottom.
  6. 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. The drawback is that the process tends to be slower.
  7. 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.

You can also watch this video tutorial: 

3. Format in Terminal (Command Line)

If for any reason, Disk Utility fails to format your drive. You can also try using Terminal, though you'll have to be a bit geeky.

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

This video also has more: 

Final words

Erasing an external hard drive or flash card can be quite easy on a Mac. With one of the above three methods, you should be able to get the job done quickly. If you have any questions during the wiping process or towards a particular method, let us know.

Meanwhile, we want to remind you again to back up all your data before you get started.

Cover image courtesy to Flickr.

Jessica Carrell

Jessica is the content manager at AnySoftwareTools. She is a lover of photography, technology, teaching, and learning. Recently she's keen on following news related to tech giants and SaaS startups in bay area.

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