So you are talking about the door trim, and not the wheel arch endpiece...ok, new plan.
You do not need to take the door panel off to do this. First thing is that black stripe that runs down the center of the door. That will *pop* out of the chanel, but be careful when doing so. After that is off, the top part of that trim will be loose from the door, but you still have the bottom to contend with.
On the inside of the door, near the bottom (and again, this is outside of the interior panel, so keep that in mind), there will be a screw that you can take out. There may be two...one on each end, but I am not clear on that. After you take the screw(*) out, you will be able to pull the trim off of the door.
Now, provided there are no broken plastic retainers, you will want to start with the top first when reinstalling, then take the palm of your hand and quickly rap near where the plastic retainers are located to seat the bottom, then apply the screws to the backside.
Let me guess....your cladding is causing the door to jam up when you open it, right?
Welcome, downwardly mobile yuppies, to the dawn of the Age of Nefarious.
1993 SSEi - FrankenJinx - dead and gone.
1994 SSE (136K strong) - 180* t-stat,HD alternator, most unequipped SSE on the club, XM radio, Kenwood CD/MP3.
2006 Chevy Malibu Maxx LTZ - Custom 2.25" manifold-back exhaust w/FM-80. Probably the only Maxx with this system.