The long, thin plastic covering that goes up the edge from the kick panel to the A-pillar is actually part of the kick panel, so loosen the A-pillar trim and get that out first. To get the rest of the panel out, I had to remove the E-brake pedal assembly.
There's an oval shaped "vent housing" section that protrudes from the backside of the kick panels. It has some raised "ribs" on the outside and is a fairly tight fit in the oval shaped hole in the underlying sheetmetal. As a result, the kick panel has to be tilted "just right" in order to pull out of the opening.
When you get the panels out, you're likely to find a bunch of sealer putty around the perimeter of the vent openings. If its still soft it can be re-used. If not, replace it with some 3M strip caulk or similar material. A poor seal here can allow water that enters the cowl grille at the base of the windshield to leak in around the kick panel vents and end up on the floor.