http://learn-share.net/erase-your-mac-securely/ How to Securely Erase Your Mac. How to erase/delete your Disk Drive in Mac OS X.
If you’re selling or passing your old Mac, make sure the recipient doesn’t get all your data!
If you’re passing your Mac to someone else, it’s seriously recommended, to you boot up from the OS X Install DVD (if your Mac has one), wipe the hard disk and reinstall OS X before you do anything with them.
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