Ya just gotta grab it and it will break off like a leg 'o turkey.
It takes a bit of a leap of faith, but grab it as though you are reaching into the car from the top, so that your fingers are under the stalk, and firmly 'break' it upwards, using the top of the windshield as the 'fulcrum.' This is how it works on my S2 (I have the light in mine). When it comes loose, it will be with enough force for you to think that it literally broke off, but have no fear. It simply snaps back into place, as well. It seems barbaric, but that is how it works... With the lights, a pair of needle nose pliars will allow you to 'unplug' the wires... I would take this time to disassemble the mirror, and wipe clean the mirror, glass, etc. They really clean up nicely.