How to turn off built-in macbook display?

Question

macOS

How to use a MacBook with only an external monitor? You need to turn off the built-in retina display, but without closing the lid.

Answer 1

In terminal, to disable:
sudo nvram boot-args="iog=0x0"
Reboot afterwards.
To enable:
sudo nvram -d boot-args
Reboot after.
But I would first try the option with a magnet.

Answer 2

No way, just reduce the brightness to zero.
ps and keyboard backlight too.