Shut down Android TV

I have a Philips 58PUS8505/62 4K LED Android TV. Normally, I want to power off the TV by switching off the power outlet the TV is connected. However, the TV or its remote does not provide a menu or key combination (that I know of) to shut down the operating system and power off the TV _before I cut the power_. When I press the red (power) button on the remote, the TV goes into standby. However Android continues to run and I see disk IO on the external disk connected to the USB port of the TV. I know how to "unmount" the external disk, but my question is not on this. I tried to **long press** the power button on the remote (external TV boxes work this way), but nothing different happens. There seems to be no way to power off the TV. What am I missing?