At any point when Carla's mental state becomes “Wrecked,” she will quit the force. The easiest chapter to unlock this trophy is in “Debriefing,” in the archives. Just keep failing the breathing QTEs, and Carla's sanity will drop by 10 each time (you'll have to get up and go back into the archives in between). Keep doing this until the game cuts to Carla quitting the force and you'll earn this trophy.
Solution taken from PlayStation Trophies:
https://www.playstationtrophies.org/game/indigo-prophecy/tro...