Trying to set up my Macbook Pro for sale

I have a Macbook Pro running Mavericks that I am selling to a friend. I googled for instructions, and followed everything in this article:

OS X Mavericks: Erase and reinstall OS X

The computer is now re-installing Mavericks. However, in order to do that, I had to provide MY Apple ID and password. How do I get it so it is like brand new, ready for my friend's ID/PW, and make sure that mine is no longer attached to the computer.

Thanks.