The steps can vary because people either use an oven or a heat gun. I personally used a heat gun because my headlights wouldn't fit in my oven, and I worried about melting some parts. Heat gun was more manageable, but it added a lot of time to the process.
Baking:
1) Remove the headlight assembly.
2) Remove the bulbs, wires, and other loose items on the assembly.
3) Place the headlight on a sheet in the oven and bake it at 250 degrees for 15 minutes. Some have used wood or cardboard to prevent "contact-melting."
4) The permaseal that seals the headlight lens to the back of the headlight assembly will begin to soften and loosen.
5) Somewhere near the bottom of the headlight, or at farthest corner the edge of the headlight, use a flathead screwdriver to pick at the permaseal and pry open the headlight while the permaseal is soft.
6) The headlight lens is made of plastic, so there is some wiggle room. Keep prying and prying until the lens is removed.
7) Keep in mind that baking at the wrong temp or for too long could result in melting the assembly or the lens; warping or damaging the assembly; etc. Oven temps vary by oven so proceed with caution. The headlight cools down relatively soon, so constant re-baking at the same temp but lower time interval might be necessary.
Heat Gun:
Similar to the above, without the oven. Use a heat gun on a low to mid heat setting and aim it along the entire edge of the headlight. The permaseal will begin to soften..... pry and pry, etc.
Once the lens is off, you can unscrew the amber reflector and ponder what you want to do to the interior (ie. paint it black, remove the amber permanently, tint the amber black, paint the chrome trim to something else, add halos, retrofit HID projectors, and so on).
Referencing the photo, the headlight lens is at the top left. In the middle, to the right, is the amber reflector housing and reflector itself. The amber reflector is screwed to the reflector housing. The reflector housing is screwed to the final piece at the bottom, left--the headlight assembly base. The base has the headlight projector mounted to it, as well as the chrome signal and side marker reflector.