How to cut power supply using arduino only

How to cut power supply using arduino only without a switch... thanks :P

Cut power supply to...? I'll assume the arduino. The power save option in arduino might be a better option. Else, you might need a .. uhh. relay which you turn off from the arduino.

lets say i have a charger circuit... and i want the circuit to stop charging when it is full.. but i need to use arduino.. not a switch.. thanks btw

A relay is what you want then :)

You ned to consider this . how do you want to tell the arduino that the battery is full ?