I don’t have a laser or a MiniRambo to test. But with that said, here is a post were I explore the differences between the Rambo firmware (which has the laser enabled) and the MiniRambo (which does not).
In thinking about it since that post, I think you can modify this line:
#define SPINDLE_LASER_PWM_PIN 9 // Hardware PWM
So that the laser pin matches whatever fan pin you are using (6 or 8 or some other pin if you have redefined the fan pint to a 5V pin), and leave the fan pin alone.