Arrrghhhh ----- Quit making things complicated...... LOOK IN THE BASEMENT for the cable from the light...... (Not outside). There is likely an octogon box on the wall. Draw a straight line from the post to the house. Measure that spot from the corner of the house. Go in the basement and measure the same distance and look for the box. Once you find it, disconnect the wires inside that box and put wirenuts on the ends. Turn you power back on and dont worry about it till you get an electrician to replace the thing.
Another thing. Is there a switch that turns off that light? If there is, remove the switch, wire nut the two wires and turn your power back on. Most likely that IS a switch.