Boot from the Recovery HD by restarting the computer and after the chime press and hold down the COMMAND and "R" keys until the computer starts from the Recovery HD. Select Disk Utility from the main menu and click on the Continue button.
2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, set the partition scheme to GUID then click on the OK button. Click on the Partition button and wait until the process has completed.
4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.
5. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, check the button for Zero Data and click on OK to return to the Erase window.
6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.
At this point all your data are securely removed. You can shut down the computer or reinstall Lion from the main menu.
First off, thank you for the detailed response. If I shut down after the erasing process, then the computer will be as if it were new the next time it's powered on, right? My replacement Air just came today so this one is being sent back, but I want to be really sure that all my data is gone before it goes back.
If you just erase the drive but do not reinstall Lion, then you will return the computer with a blank drive, not as if it were new.
However, the computer you are returning will only be resold as a refurbed unit, so Apple will install whatever software needs to be installed on it. You are not obliged to do that yourself unless you want to.
If you follow the drive prep procedure I provided all your data is essentially securely erased. That is what the one pass Zero Data Security option does.
Yep, you've erased the drive (not securely) so now it's not bootable. Again, boot into the Recovery HD by restarting and after the chime press and hold the COMMAND and "R" keys until it boots from the Recovery HD.
Follow the previous procedure from Steps 4-6 to simply do a secure erase of the Macintosh HD volume.
Oh man I give up. The new Air is nothing but problems... I did the Command-R on reboot and got to a recovery screen, but it can't move forward because it can't connect to the internet. I've tried everything to connect and it just won't connect. I've changed the wireless access point from WPA/WPA2 Personal back to WEP, I've made sure that the access point is being broadcasted and not hidden... Nothing will work. And I know that the password is correct because I have it written down and I tested it with this MBA and my Palm Pre. Nothing will work ack ack. I think I'm just going to send that stupid MBA back and let Apple deal with erasing the data :\
So frustrated right now with Apple and the stupid things they are doing with Lion.
I have had the same problem...security option is greyed out. I followed your steps perfectly to the point I went back in by holding down the Option key at start up, connected the wifi, went back into disk utility and followed your steps again, still no security option. Is the security option not available because it's SSD?
I erased the partition and did a clean install of Lion as I couldn't get a secure erase. Very frustrating.
This is how its done:
It works on Mac OS X Lion only.
1. Launch the Terminal application on you Mac. Then run the following sequence of commands (one at a time):
dscl . -delete /Groups/admin GroupMembership yourAccountNameHere
dscl . -delete /Users/yourAccountNameHere
2. Now reboot your Mac into single-user mode by holding Command-S at startup.
3. Once booted into single-user mode, run the following sequence of commands (one at a time):
/sbin/mount -uw /
rm -R /Users/yourAccountNameHere
mv .AppleSetupDone .RunLanguageChooserToo
rm -R /Library/Caches/*
rm -R /System/Library/Caches/*
rm -R /var/vm/swapfile*
Your Mac will reboot to the start of the initial Apple Setup program just like when you first powered it on after purchase. All clean and ready to sell or give to a new user.