Quote from another forum:
"Unscrew the 2 torx screws holding the top of the headlight (I assume the middle screw holding the bit of plastic is used as a guide for putting the unit back in). Then all you need to do is push the unit out, give it a bit of a wiggle (up and down holding the back of the unit worked best for me) as it will probably be a bit stiff.
Remember to disconnect any cables connected to the light unit before pulling it out, you do get a bit of play on the cable length.
When sliding back in there are 2 clips/slots that the bottom of the light unit slides into so remember to line them up."