I disconnected the power connector first from inside the engine compartment. Attached a string to that antenna connector to hel fish it back up into the right place after installing the new/repaired unit.
Then drop the antenna down and remove the coax cable like the above members stated.
FYI: Be careful opening the door during this operation. When removing some of the fender bolts, (from the underside and in door jam.) The fender may hit the door edge. (Also, tape a small piece of cardboard to the outside of the door when working on the bolt in the door jam.) You'll see what I'm talking about once you get started.