Depending on what you are trying to energize and de-energize and how (more details please), I would say either a SPDT (single pole-double throw) switch or a DPDT (double pole-double throw) switch.
i am altering my rc rock crawler with 4 wheel steering i soldered together a y harness for the servos and it works great but i have a third channel that is just on and off would like to take the third channel into some sort of switch that i could in turn open and close the control wire to the rear servo to turn on or off the rear steering they make $300+ radios that do it but what fun would that be and i don't have the money
So, you need an electromechanical relay or a solid state equivalent circuit. Since R/C isn't my specialty, could you provide a wiring diagram or a link to the manual for the receiver?