Reinstalling OS X, but disc is locked and serial number is registered to previous owner
I bought a used MacBook pro from a friend, He deauthorized the computer from his Itunes account and took all of his files.
Now I'm attempting to wipe and reinstall mavericks from the restore screen and my "disc is Locked"
When I try to unlock the disc, I find that the general advice is to make an appoinment with the Apple store, BUT the serial number of my computer is still assigned to the previous owner.
How can I (1) legally get ownership of this computer
2 unlock this disc?
Thanks,
S
MacBook Pro (13-inch Mid 2009), OS X Mavericks (10.9)