Formatting and erasing sensitive data when selling old laptop


I am selling an old MacBook Pro and was wondering what procedures you follow to format and erase all sensitive data?

Thanks for the input

This article gives a whole bunch of options for several situations.
I myself would probably use filevault to encrypt the drive, and do a “quick” wipe on my macbook pro.

1 Like

That should be enough, that’s what Apple asks you to do if you are returning back a Mac for TradeIn. Make sure to sign it out of iCloud, and see if you are using this device to authorize purchases, make sure to disconnect it from iTunes and different services.

Also if you have license per seat, sometimes it is difficult to revoke a seat if you do not have the original hardware. So check that as well.


From what I’ve read it would appear the terminal command mentioned in the Backblaze article:

“diskutil secureErase freespace VALUE /Volumes/DRIVE” is not effective on SSDs.

In NIST SP 800–88 it says Degaussing and overwriting techniques - common methods for sanitizing magnetic media - are not applicable for flash memory devices. Evolutionary changes in magnetic media also have impacts on sanitization. New storage technologies, and even variations of magnetic storage, are dramatically different from legacy magnetic media.

The Department Of Defense (DoD) Media Sanitization Guidelines 5220.22M has similar language.

1 Like

That’s so true. I contacted developers to inform them prior to removing software and that worked.

1 Like

Be sure to turn OFF all find my mac stuff before doing any erasing.


Assuming you have access to decently fast and unmetered Internet:

  1. Sign out of iCloud (and Find My Mac, especially).

  2. Boot into Recovery

  3. Use Disk Utility to delete the boot drive and ‘Data’ partitions.

  4. Re-Install macOS

Unless you have government secrets on your computer, that should be sufficient.


Since I always use encrypted file systems (and within the encrypted file system there’s added encryption for really sensitive stuff), a simple “nuke and pave” is good enough for me.

1 Like

Thank you for all the replies. Followed the advice and encrypted drive, logged out of all accounts, formatted and re-installed.