Now select the partition again in Disk Utility and under the “Erase” tab choose “Mac OS Extended (Journaled)”.

Have the disc erased and turned into an encrypted format, this process may take a while depending on the disc type, size and speed.

Choose “Erase” and set a password for the encrypted partition, now choose a simple password that is easy to remember, then choose “Erase”.

Under “Format” choose “Mac OS Extended (Journaled, Encrypted) – the” Encrypted “part is crucial.

Select the primary hard drive partition on the left (commonly referred to as Macintosh HD) then choose the “Erase” tab.

Choose “Disk Utility” from the OS X Utilities menu.

Restart the MacBook, hold down the OPTION key and select the recovery partition.

The most obvious solution to this problem is to boot the Mac from an external startup disk (here is how to make one for Mountain Lion), but that’s not always an option for everyone, but luckily there is a solution that allows you to perform a safe wipe directly from the recovery partition itself.

Still, many users want the ability to securely delete data from SSD. The exact reason for this isn’t entirely clear, although some speculate that writing 1’s and 0’s to an SSD can lead to performance degradation and a shortening of the drive’s lifespan, and this persists even in the most recent versions of OS X, suggests it’s not just a bug. The latest Macs come with a recovery partition instead of a separate external reinstallation disk, and if you’ve ever rebooted a newer Mac, iMac, MacBook Air, or MacBook Pro with a recovery partition SSD to reformat the drive, you may have noted that by default the “Security Options” button is grayed out in Disk Utility options, seemingly preventing a standard “secure” erase procedure.

Mac disk utility secure erase