If you look down from on top of the light, you will see the clip where my arrow points at. It's kinda like a barbed clip. You push this down then the light will slide out. I found that you had to wiggle it from the top and the bottom as it was very stiff.

Eventually it will pop out and you can get a good look at the clip.

Once you have the unit in your hand, you will see the wiring and holder for the indicator bulb (you can see it in the above pic). Change your bulb and get ready to refit the complete unit.

You'll see from this next picture, how the unit is fitted and probably why it's so stiff and a pain in the arse to remove. The whole thing slides into some guides on the headlight!