[sdh9]

Every airplane type is a bit different, but typically, if the aircraft is powered then the CVR is recording. Even if it’s at the gate with nobody onboard— the CVR does not know nor care.

The only way to stop the CVR from recording is to depower the airplane (which is one of the steps you take prior to an emergency evacuation) or to pull the circuit breaker if the airplane needs to stay powered.

A pilot would never pull the circuit breaker without confirmation from management or safety to do so. It’s just not done routinely. Depending on the airline, it may not even be the pilot’s responsibility to do so. Every airline has a binder (likely, several binders) full of procedures to follow after a NTSB-reportable accident. No one person is expected to do the job of many.