Configure MBP back to factory but with most recent OS
Download OS X from the App Store and create a USB Installer. 
Boot the Mac from the OS X USB Installer and use Disk Utility to create a single Mac OS Extended (Journaled) partition and then install OS X.
After the installation and the setup of the first user were finished boot to Recovery Mode
Disable System Integrity Protection with csrutil disable entered in Terminal.app
Reboot to Single User Mode and enter /sbin/fsck -fy and /sbin/mount -uw /
Remove the first user ($user) from the local directory db with dscl and its user folder /Users/$user with rm (hint)
Remove the file .AppleSetupDone with rm /var/db/.AppleSetupDone
Reboot to Recovery Mode and reenable System Integrity Protection with csrutil enable
Finally shut down the Mac