You just Delete the account on the MBP. Deleting an account on one system has no effect on any other system, computer, phone or pad.
But what you are doing isn't necessary so to speak. What you should do is erase and or repartition the drive as one partition and reinstall OS X. You can not sell or give away a Mac with one of the Download only version of OS X, Lion or Mt Lion, IF that Mac came with an earlier version of OS X on it when it was new. If you upgrade OS X from an early version to one of the Download only versions that version of OS X is Tied to Your Apple ID and can not be transfered to another person. And if you upgrade from Lion to Mt Lion you have to reinstall Lion before you can sell it or give it away. Again upgrading to Mt Lion from Lion Mt Lion is Tied to Your Apple ID not the machine.