how to I factory reset my Mac book pro

What to do before you sell, give away, or trade in your Mac - Apple Support

Hi,

Start up in Recovery Mode then reformat the internal drive with DiskUtility and reinstall macOS should be factory setting.

How to reinstall macOS - Apple Support

Hi,

Start up with Shift+option+command+r will install the macOS which came with when you purchased your McBook Pro.

I want to factory reset my MacBook pro