Remove the seatbelt cover. This is held by two mini clips on either side of the cap. They are flexible so you could just pry the cap off, but if wanted, use your flathead screwdriver to poke the clips out of place and remove the capping.

This panel has 3 clips very similar to the rear tabs highlighted in step 5, as well as one big screw.

Use either a big Allen wrench or a pipe wrench to remove the big screw under the capping.

Gently pry each corner of the panel away from the wall to disengage each of the 3 clips, and the panel will pop out.