How to turn off the Arduino on Delta 432?

Hello everyone, I am fairly new to the LattePanda universe, so please be gentle with me.

I installed Linux Ubuntu 16.04 on my LattePanda Delta 432 to have a Dual boot option with Win10.

I have a "program" that does nothing more than setting one Pin (D4) of the Arduino GPIO to high.

Now I am looking for a way to turn off the Pin, (or the whole Arduino) via a bash command (or multiple commands.)

I don't want to open the Arduino IDE or giving any form of other input than these commands to turn off the Pin, because I want to pack them them in a script that is executed automatically upon startup of the Arduino.

So basically, as soon as I press the power button on my LattePanda the pin goes to high, and I want it to go to low as soon as the LattePanda finished booting, therefore I thought of maybe just disabling the Arduino alltogether when it finished booting.

For what it helps, this is what is running on the Arduino at the moment:

void setup {
pinMode(4, OUTPUT);
digitalWrite(4, HIGH);
}

void loop {
}

Thank you all in advance!