You mean the vents at the side? The ones in the middle point pretty far down on my car. The ones on the side don't appear to go below level (without help) but it's a pretty quick tweak to get them to point as far down as the center ones.
To remove the vents, just grab and yank up, slightly forward. There's a plastic lip along the back edge and two front metal spring clips holding the plastic shroud in place. With the assembly out, it's simple to pry the bottom apart to extract the vent held in place by a round edge in a round hole around the center. With the vent in hand, you'll notice two sets of black plastic "ears" on the top (see image top left). If the pair furthest forward (image lower left) are removed - not just snapped off as in the bottom image but snipped or cut cleanly off (lower right) - the vent will be able to point as far down (top right) as the center vents do in my car.
Reassembly is simply pushing the vent back into the shroud so that everything settles back to normal (tabs go on top) and putting the shroud back into the dash.