How can I reset MacBook Pro A1278 to factory settings

Yes. It will be very simple.

Power down your mac. Hold down the option key on startup.

You will see disk utility. Go in disk utility and click the erase button for your HDD data.

Then go into install OS X and install the operating system.

It will be a completely fresh install ready for selling.

Just follow these instructions:

http://www.thesafemac.com/how-to-prepare-your-mac-for-sale/

Ciao.