Power Steering Flush

Gotta tell ya that I've never heard of anyone flushing their PS system. I've managed a Firestone service center and worked at a few other automotive shops in my 50-years.

But if you really want to - you could disconnect one of the hoses and let it drain out.
 
it is very important to flush the powersteering fluid on fords. there are many ways of doing it, the most common way is to remove the reutrn line, plug the resivoir and run the motor turning the wheel back and forth while putting in fresh fluid. you know youre done when the fluid coming out the return hose is the same color as the fluid you are putting in. i would suggest using a synthetic ATF like mobil 1 or Redline for the fluid. not servicing the power steering is a major contributing factor to the dreaded ford power steering groan.