First off, I would suggest you stay away from attempting to remove the rear panels in the driver side. That's where the electric switch for the seats and the charging port connectors are and if you mess something up, you will have to come out of pocket for a trip to the service center.
With that said, in order to remove the side panels in the trunk, the load floor panels have to come out first.
1. remove carpeted load panels
2. remove the long strip of molded plastic piece that held up the floor panels, one on each side (pops off from the floor with pins clips)
3. undo the weather strip around the hatch (put something around it to keep it from having black silicone smeared all over the place)
4. remove rear hatch sill panel (pops away from the body with clips but be careful not to break any of the pins)
5. remove the rear side well/pocket panels (pops away from the body with pins)
6. remove lower side panel (pops away from the body with pins and upper panel with clips, again careful not to break them)
7. remove upper side panel (pops away from the body with clips)
Only then, you will be able to wedge a gap in the headliner from the rear. Key phrase here is TAKE YOUR TIME. The plastic panels and pins are brittle and prone to damage quite easily. Good luck!