How to Secure Erase Disks on MacOS Tahoe & Sequoia

Whether you’re preparing to sell, recycle, or repurpose a Mac, or you’re going through old hard drives and storage disks that you wish to clear all data from, securely erasing the drive is an important step. Simply deleting files or formatting a disk isn’t always enough, especially for hard drives and external storage, since data can sometimes be recovered with recovery and forensic tools. The last thing you want is to discard an old hard drive with some important data or private information on it, and then have that data be recovered and used for nefarious purposes. Securely erasing disks and hard drives is particularly important for many professions that work with a lot of private personal data, like as is common in human resources, payroll, medicine, healthcare, CPA, or financial advising.

On modern Macs, including with MacOS Tahoe and Sequoia, the options to secure erase a drive or disk can be a bit more nuanced than they once were. Sure, sometimes you can simply connect a drive to the Mac and use Disk Utility to secure erase, but you might also find that the familiar “Security Options” settings in Disk Utility are not always available, depending on the type of storage device that is in use. This has led some users to believe that secure erasing is no longer possible in MacOS with Disk Utility, but that’s not necessarily the case. While this can be confusing if you’re expecting to secure erase and overwrite a disk the traditional way, it does not mean that you cannot securely erase disks and drives anymore, but you might need to look beyond Disk Utility to achieve this objective.

We’re going to run through the steps to use secure erase for disks and drives on modern Macs, with MacOS Tahoe 26 or later, and what to do when the standard security options feature is not available within Disk Utility, so that you can perform a secure erase on the drive/disk anyway.

How to Secure Erase in Disk Utility on MacOS Tahoe & Sequoia (when “Security Options” is available)

1. Open Disk Utility on the Mac (found in /Applications/Utilities/)
2. Connect the drive/disk you wish to securely erase
3. Click on “Erase” as usual
4. Look for the “Security Options” button and configure your secure erase, proceeding as usual

Assuming “Security Options” is available for erasing the selected disk, you’ll see options for choosing how thoroughly you wish to overwrite the disk, from a quick erase, to multiple passes of writing randomized data onto the disk.

This method is straightforward and pretty simple, and many Mac users over the years have come to rely on Disk Utility for this purpose, where writing and overwriting data is the standard method to prevent recovery and to securely erase a drive.

But, unlike earlier MacOS versions with Disk Utility, the “Security Options” and secure erase is not always available on modern versions of Disk Utility in MacOS, depending on the MacOS version, and the drives in use, as you may have noticed by now, so let’s explore why that is, and also cover how to securely erase a disk or drive when that option is not available to Disk Utility.

Why “Security Options” May Not Appear in Disk Utility on Mac

If you don’t see the “Security Options” button when you attempt to erase a disk within Disk Utility on the Mac, it’s probably by design. Apple has specifically removed the secure erase feature for certain disk types, including SSD’s (solid state drives), internal onboard storage on an Apple Silicon Mac, APFS formatted volumes, and sometimes even older traditional spinning SATA hard drives and hybrid disk drives. The latter spinning drives are often used for archival and backup purposes, making those drives particularly important to securely erase, if they contain personal, sensitive, private, or professional data.

You will typically not find the security options available on SSDs because of wear leveling and other techniques used that make the standard overwrite based security approaches to erasing data less reliable. Instead, MacOS relies on encryption for those drives, and fast erase methods, to make the data inaccessible.

And for internal disks and SSDs, MacOS relies on FileVault (when enabled, which it is nowadays by default), which when erasing a disk destroys the encryption keys, rendering any previous data on the drive unreadable and inaccessible.

Important Considerations for Secure Erasing Disks via Terminal

Before performing any secure erase on any disk, you’ll want to make sure you properly identify the disk and disk identifier, so that you do not erase the wrong drive. Additionally, you should backup any important data, because secure erasing the disk makes it near impossible to get data from. Be aware that secure erasing disks can take a long time, especially on larger drives, and older spinning traditional HDDs and hard disk drives.

Also, keep in mind that SSD’s do not have the same benefit to performing repeated overwrite passing, but may reduce the lifespan of the SSD drive.

How to Securely Erase a Disk on Mac with Terminal, When Disk Utility Won’t

Even if the “Security Options” choices do not exist in Disk Utility for you, you can still securely erase a disk on the Mac. However, you will have to skip Disk Utility and instead rely on the command line. This is more advanced so if you’re not comfortable with the command line it’s probably best to skip this. If you point the erase utility at the wrong drive, you will erase the disk and not be able to recover it.

1. Open the Terminal application, from /Applications/Utilities/
2. Identify the disk you wish to erase by using the following, looking for the disk identifier (ie; diskX) that matches it:

diskutil list

3. Now use the ‘secureErase’ followed by the level of passes you wish to do on the secure erase, and point it at the disk identifier, for example:

diskutil secureErase 2 /dev/diskX

4. Hit return to begin the secure erase process

You can also use just 0 for a single pass zero fill (writes 0’s all over the disk), which is fast, but less secure.

diskutil secureErase 0 /dev/diskX

If you have particularly sensitive data on the disks, the more passes done will make the data more difficult to recover. You can use ‘3’ for 35-pass erase, which is quite slow, but means the disk is written over 35 times with random data.

How to Securely Erase Internal SSDs on Modern Macs & MacOS Versions

For most modern Macs, to properly erase the built-in internal SSD with a modern MacOS version, you can simply do the following:

1. Make sure that Filevault is enabled ( > System Settings > Privacy & Security)
2. On Apple Silicon Macs, use Erase Assistant from System Settings > General > Transfer or Reset
3. Reboot the Mac and either reinstall MacOS through Recovery Mode, or by using a bootable install drive to perform a clean install of MacOS Sequoia or Tahoe

This works because the data was encrypted with FileVault, and erasing and removing the key effectively secures the drive data.

On Apple silicon Macs, using Erase Assistant or performing an erase and then clean install of a new operating system is often the easiest and most complete method.

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As you can see and probably already discovered by now, the secure erase features of Disk Utility have changed, depending on the disks that are connected and types of disks. It’s no longer as simple or obvious as it once was, and you might now need to either turn to the Terminal as outlined above, or perform a simple disk erasure and reinstall of MacOS for an internal drive. For older Macs and drives, overwriting the disk with secureErase is effective, whereas modern Macs and SSDs can depend on encryption, standard erasure, and destruction of the encryption key.

Have you noticed the missing Security Options in Disk Utility? Did you use Terminal instead, or rely on encryption based erasure of the data on the Mac? Share your thoughts and experiences in the comments.