There are a couple ways to do this. Other drones might have their own commands or buttons to turn it off, but first off there are really 2 ways.
When you land the drone and hold down the altitude button, the props stop spinning and turn off automatically.
The 2nd way is if you started them spinning and not flying the drone, but want to just shut it off, then pull the controller levers down and in both at the same time and hold it there. It shuts off.