Format MacBook Pro

while your macbook starting keep clicking the option key tell you receive the option of recovery

cjeck the below link

http://www.apple.com/osx/recovery/

What version of OS X did your computer originally ship with?

Did you upgrade to Mountain Lion?

Ignore the above post until you answer these questions.

You have to Reinstall the Original version of OS X that Came on your system. you can not give or seel it to anyone with any newer downloaded version of OS X installed.

What year was your Mac made? What version of OS X was originally on your Mac when you bought it?

If your computer shipped with Lion the first thing you need to do is deauthorize your computer for all that you've purchased with iTunes. Then, following Kappy's advice:

Install or Reinstall Lion/Mountain Lion from Scratch

Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.

Boot to the Recovery HD:

Restart the computer and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.

Erase the hard drive:

1. Select Disk Utility from the main menu and click on the Continue button.

2. After DU loads select your startup volume (usually Macintosh HD) from the left side list. Click on the Erase tab in the DU main window.

3. Set the format type to Mac OS Extended (Journaled.) Click on the Erase button and wait until the process has completed.

4. Quit DU and return to the main menu.

Reinstall Lion: Select Reinstall Lion/Mountain Lion and click on the Install button.

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

Are you going to sell this computer? If so, you can only sell it with Lion on it...not Mountain Lion.

Please confirm your intentions.

Clinton, that will NOT reinstall Lion.

DO NOT follow Clinton's post until you answer the question about what you're trying to do.

The OP pretty much explains what he/she is trying to do.

Clinto

Please confirm your intentions.
I want to sell my MacBook Pro to another person

Just open iTunes and under the "Store" menu select "Deauthorize This Computer".

Clinton

1. Reboot your system.
2. Press “option” and choose your boot drive.
3. Select the recovery partition even it says only for OS Mountain Lion 10.8.
4. Now erase your whole disk using disk utility...importany you erase all partitions.
5. After deleting all the data, select "Reinstall Mac OS X". (Make sure you’re connected with an Ethernet cable or WIFI which uses the WPA/WPA2 authentication. Your system will automatically check which system it needs and reinstall it (usually the pre-installed version) from the servers of Apple. For example, if you bought your Mac with Lion installed, then Lion will be reinstalled smoothly; if you bought Lion from the Mac App Store, you will be prompted to enter the Apple ID and password you used to purchase Lion.)

Important: 1) Make sure that all your partitions are erased before reinstalling; otherwise it doesn't work or will reinstall OS X Mountain Lion instead.