SCjon.....in answer to your question....VERY carefully!
No seriously. I haven't taken off a side door panel yet, but I would assume like most cars it has a combination of screws and clips.
I usually use a metal yardstick that I slide in beneath the panel to start locating the clips. Then I pop them out one at a time until the whole panel is free.
But back to the "very carefully" part. It is possible to break or bend these clips leading for the hunt for replacements which can be like trying to find a needle in a haystack for part numbers. Be ginger with it and it'll eventually release. I believe most of the interior panel clips that I have seen in the nitro are a combination plastic with metal.