If my flight is delayed and I decide to get off the plane and not travel do I need to do anything special to let anyone know?

Great question, and the answer is yes! If you already boarded the flight the airline shows your ticket as “used”. If you then de-plane you must stop at the desk and have the airline agent re-open your ticket for future use. It can be extremely difficult to have this done later if you don’t take care of it right away.