I used a flat screwdriver, tried to pry up a tab while putting pressure on the mirror with my other hand. I think if you push closer to the centre of the mirror, the better. Then I tried prying up another tab. Eventually it popped off. I started with the mirror all the way down and towards the car and used the exposed corner. I found, though, that when the mirror popped loose, it got wedged in the housing. I had to tilt the mirror toward a more normal position and was able to remove the glass. I didn't disconnect the wires for the heated mirrors, I lowered the front windows and just let it rest on the window sill.
I *may* attempt to do this again, to put in brighter puddle lamps... lol