Sunroof drain tubes location and clogged

[PacoDeth]

So the front drivers side drainage tube for the sunroof appears to be clogged and is letting water into the car.

I've tried running trimmer line and a plastic coated wire cable but cannot clear the clog. The wire goes pretty far down into the tube from the sunroof entry point, but then stops.

So my first question is where is the exit point under the car where this tube lets water out from as I have thus far been unable to find it.

Secondly, how do you get the pillar material off to inspect the tube where it runs down the car door above the window?