Can heat pumps be turned off?

There should be no need to turn off a heat pump as the thermostats within the house maintain a certain temperature throughout the house.  

When the room or 'zone' reaches the required temperature, the heat pump will go into standby mode (if the demand for hot water is also met). If you feel the house is too warm, you can turn down the thermostat for the room or 'zone'. 

Your heat pump should be serviced annually to ensure optimal performance and extend its lifetime. There's no need to turn off your heat pump before your annual service.