This method will remove the condensation and any water marks. You have to remove the headlight from the car. With the lens of the headlight laying flat down on a table poor a small amount of 99% methanol into the corner marker light hole. Swish it around the lens, and then poor it back out of the marker light hole. Do this a couple of times. WARNING - You must let the headlight thoroughly dry out before putting the headlight back in the car and turning it back on.

You can buy the methanol from Amazon: