There is an Access Panel in the wheel liner (you may have to turn wheel inward to access). Open access panel and locate Slider Mechanism, high on the back of the headlamp, slide it upwards to release the lamp. Then pull lamp forward away from vehicle. There is a Ball Stud and Socket holding the Lower outboard corner you will have to overcome. DO NOT loosen or remove screw that is visible through the opened access panel. On DS it has no effect on headlamp removal, it is part of the carrier assembly. Be sure to replace fender to headlamp wedge if it falls off.
Ahhhhh......you had 2009 in your question.......ok no problem.
Grasp the lamp firmly and pull straight forward to disengage the ball stud on the upper outboard corner of the lamp from the plastic grommet (1) in the mounting panel.