Hello,
Is there a way to cut off and turn on 5V pin on 40-pin header ?
Thank you very much
@ptphucbk you can put in a transistor/mosfet connected to the 5V and any one of the GPIO pins with some coding to control it 
@Electr1 Thank you very much.
Is there a built-in feature like that ?
If no I will try out your solution.
the 5V power rail is managed independently by the power regulatory circuit, hence there is no other options…
It is possible to do this at the software level, but the question has never stood that way, enable or disable these contacts, perhaps if you can implement it programmatically.