I have just changed my z_min mechanical switch to a proximity sensor, so I won't be needing probe deployment or retraction anymore. Can someone point me to how this is done in Marlin?

Thanks

In marlin, you have to build up the firmware from scratch and reflash it with the Arduino IDE ( erase EEprom first ! ) If you are lucky and have the current FW at hand, you can search the ABL-section of config.h for the deploy definition and outcomment it ( put // in front of the #define )