Unplug it if you want no power use, same as most electronics, everything goes into power saving mode now so that it is there when you need it, in the case of a printer, it goes to a very low state and waits for you to either hit the power button or send it a command via USB or LAN/WiFi.
This is the measured power draw in each state (source)
Hello, I recently bought this device and I cannot figure it out how to turn if off, because I rarely need to print something and don't need to be ON 24/7 and consuming power? I tryed with holding power button. but it won't turn off like my previous printers. Any ideas?