Manual mesh bed leveling

hi,

I'm working on a project which involves modifying a Prusa i3 MKII, I want to cancel the auto bed levelling and replace it with a manual mesh bed levelling.

I have checked the printer's firmware and I found the settings for the auto bed levelling and nothing for the manual mesh levelling, in Marlin firmware, there is both of the settings for the auto and the manual.

my questions is how can I disable the auto bed levelling and replace it with manual bed levelling? I don't know what to remove or add exactly from the code