Securely delete a user account from your Mac

There are many reasons users may want to securely delete a user account from their Mac. Certainly if you are planning to sell your Mac or give it to someone you do not want your information lingering on the machine.

There are several ways to delete a user account, some more effective than others.

1. Drag the user home folder to the trash and securely empty it. While this will delete most of the content from a user's home folder, it will not delete all the information on a computer left by that user. 
2. Apple Support Discussions user "Király" suggests:

"The method I like to use is to enable FileVault on that account, and then delete the account with System Preferences -> Accounts.

Another method is to delete the account first, and then run Disk Utility's Erase Free Space feature. This is just as secure but it takes much, much longer.

However, deleting accounts won't get rid of everything. Some user data gets written to /private/var/folders. I have found copies some of my e-mail attachments and even my web browsing history in there. This data lingers on even after deleting the user account. If this is a concern, and if you are really truly worried about data security (i.e. you are selling your Mac), I'd use Disk Utility to reformat and zero out the whole hard drive."

FileVault secures a user's home folder by encrypting its contents. To turn on FileVault, navigate to System Preferences > Security > FileVault. You will need to set a master password for your computer before you continue. Once you have set your master password, click "Turn On FileVault...".

To zero out the entire hard drive, install your Leopard Install DVD and hold 'C' while restarting. Choose Disk Utilities from the Utilities menu and choose to erase. You can set the number of passes your computer will make while deleting as well. If you are selling your computer, you will definitely want to zero out your hard disk, ensuring no personal data remains on your drive.

As always, be sure to retain a back up copy of your information in case you change your mind during the process or would like to have your data transferred to a new machine.

Resources
Read this Apple Support Discussions thread about securely deleting user accounts on your Mac.

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Resources

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