Remove the screws from the lower seat belt mount, the lower edge of the upholstry, the door handle, and the knob to adjust the mirror. You can remove the lower section, now.
On the door handle, one screw is visible, the other is covered by a small plastic panel that will pop off with a flathead screwdriver.
Pop the guard off the top seat belt section where it enters the door. Unscrew the metal plate. You'll still be unable to get it out of the door, that comes soon.
There will be several 7mm bolts along the newly exposed section. Remove these, and the one behind the door handle panel (by the interior handle).
Firmly pull the upper upholstry away from the door, it's held in by plastic fasteners all along the edge. It's a little difficult to get it off from around the door handle. You may now use a flathead screwdriver to remove the metal clip by the seat belt, and slide the belt out of the door.
Yes, it's a lot. It's easier to put it back together, just make sure you don't have any spare parts when you're done.