How do I permanently erase my entire MacBook Pro 2011?

Click here and follow the instructions. When you reach step 5, insert its original disk, restart with the C or Option key held down, use the Disk Utility to erase the internal drive, and install a fresh OS.

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Before Selling or Giving Away Your Pre-Lion Mac

1. Deauthorize your computer from iTunes, if applicable.
2. Back up your data using Time Machine or other backup methods for OS X Mavericks or Mountain Lion.
3. If you use Find My Mac or other iCloud features on this Mac, complete these steps:
   1. Back up your iCloud content.
   2. Choose Apple Menu () > System Preferences, then click iCloud.
   3. Deselect the Find My Mac checkbox.
   4. Sign out of iCloud. When you sign out of iCloud, you're asked whether you want to remove iCloud data from your Mac. Removing iCloud data in this way makes sure that the data isn't also removed from any of your other devices that are using the same iCloud account.
4. If you're using OS X Mountain Lion v10.8 or later, sign out of iMessage:
   1. In the Messages app, choose Preferences > Accounts
   2. Select your iMessage account, then click Sign Out.

5. Follow these steps for installing the original version of OS that came with the computer.

1. Boot the computer using the Snow Leopard Installer Disc or the Disc 1 that came

with your computer. Insert the disc into the optical drive and restart the computer.

After the chime press and hold down the "C" key. Release the key when you see

a small spinning gear appear below the dark gray Apple logo.

2. After the installer loads select your language and click on the Continue

button. When the menu bar appears select Disk Utility from the Utilities menu.

After Disk Utility loads select the hard drive entry from the left side list (mfgr.'s ID and

drive size.) Click on the Partition tab in the DU main window. Set the number of

partitions to one (1) from the Partitions drop down menu, click on Options button

and select GUID, click on OK, then set the format type to MacOS Extended

(Journaled), then click on the Apply button.

3. When the formatting has completed quit DU and return to the installer. Proceed

with the OS X installation and follow the directions included with the installer.

4. If you are planning to sell or give your computer away, then do the following:

After you reformat your hard drive and reinstall OS X, the computer restarts to a

Welcome screen and asks you to choose a country or region. If you want to leave

the Mac in an out-of-box state, don't continue with the setup of your system. Instead,

press Command-Q to shut down the Mac. When the new owner turns on the Mac,

the Setup Assistant will guide them through the setup process.

Note: Portions of the above have been copied from What to do before selling or giving away your Mac - Apple Support.

Since you have Yosemite, you might have a CoreStorage Logical Volume Group (LVG). Open Terminal from /Applications/Utilities and type the following. Post the results here. If you have an LVG, you will want to revert it or delete it before you erase your Macintosh HD and reinstall your OS X that originally came with your Mac.

diskutil cs list

fndoye69 wrote:

IIs that was user Kappy has posted as step # 5 in his reply on this thread?

No.

Open /Applications/Utilities and launch Terminal.

Type: diskutil cs list and check towards the bottom of the output for a line that says Revertible: Yes. If it says Yes then let me know or post the entire output from the diskutil cs list command here.

http://www.thesafemac.com/how-to-prepare-your-mac-for-sale/

fndoye69 wrote:

It says No. It is not revertible.

Ok, then you will need to delete the LVG. You will need to boot your system using an external boot device like a USB thumb drive or USB drive with a clone or something. So, you can create USB thumb drive with the Yosemite Recovery HD on it by downloading and running the OS X Recovery Disk Assistant. This works with OS X Lion and above. Use a 4GB thumb drive. Then boot from this thumb drive which will take you into the OS X Utilities menu and follow the instructions below.

Boot off an external device with the Yosemite Recovery HD.

Select Utilities/Terminal from the OS X Utilities menu bar.

Type: diskutil cs list to get the Logical Volume Group's UUID. This will be the 1st line of output that looks similar to the following example.

Example:

|

+-- Logical Volume Group E03B3F30-6A1B-4DCD-9E14-5E927BC3F5DC <--UUID

======================================================

Next, type diskutil cs delete UUID (replace UUID with the string of letters/numbers/dashs like the example above).

Restart your system using your factory install OS X installer. This might be a Snow Leopard DVD or a USB thumb drive with the factory OS X install or you may have to restart using Internet Recovery using the Command+Option+R keys to boot to Apple's server to reinstall the factory OS X.

Use Disk Utility to format your Macintosh HD. It should have already been formatted after issuing the diskutil cs delete command.

Reinstall OS X that was shipped with your Mac.

After install and at Setup, shutdown your Mac and it's ready to sell.

Deleting the LVG puts your Macintosh HD back to the native type format of Mac OS Extended-Journaled so your buyer doesn't have to deal with that stupid CoreStorage disk format. Apple, for what ever reason, decided to format Mac laptops to this CoreStorage format when installing Yosemite which can confuse some customers when they try to partition their drive or manage it.

Since you mentioned your system came with OS X Lion, you might be ok to just do an Internet Recovery (Command+Option+R) to erase your Macintosh HD and reinstall OS X Lion.

You don't have to do anything I wrote. You can just do that link you referenced and you might be fine. I was simply trying to get your disk back to how it was before you installed Yosemite.

Install OS X Using Internet Recovery

Boot to the Internet Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND-OPTION- R keys until a globe appears on the screen. Wait patiently - 15-20 minutes - until the Recovery main menu appears.

Partition and Format the hard drive:

1. Select Disk Utility from the main menu and click on the Continue button.
2. After DU loads select your newly installed 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. Click on the Options button, set the partition scheme to GUID then click on the OK button. Set the format type to Mac OS Extended (Journaled.) Click on the Partition button and wait until the process has completed. Quit DU and return to the main menu.

Reinstall OS X: Select Reinstall OS X and click on the Install button. Be sure to select the correct drive to use if you have more than one.

Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.

This should restore the version of OS X originally pre-installed on the computer.