Is it illegal to have a smoking hotel room without a battery in the fire alarm?

Normally in a hotel you would not have battery operated smoke alarms. You would have a mains powered fire alarm system connected and networked throughout the hotel building. In this case, heat detectors may be installed as they do not detect smoke...only heat. Although, removing the detector head or disconnecting the detector is illegal and dangerous as it may disconnect the rest of the fire alarms in the hotel and for your electrical safety.