Search for the thread that has the actual PDF instructions. The mirror itself will slide up to unlatch NOT out towards you. I recommend using a large wedge shaped instrument - for example, the end of a crowbar (what I used).

Wrap it in a towel/cloth to protect the mirror and plastic trim. Put it between the bottom of the mirror and the mirror assembly. Lever the crowbar up to push the mirror up - it will take some force. Just go slow and it'll eventually pop up. Like someone else said, move the mirror so that its facing down towards the gorund to get better leverage.

You want a WIDE instrument so you can distribute the pressure on the bottom edge of the mirror. A Wide chisel would probably work too.

Good luck!