If your on about the rear qtr interior panels, then you have to un bolt the belt on a single nut, pull the door rubber away from the edge amd carefully pull it off the clips.
With regards to the leak, make sure the door rubbers are pushed down properly, check to see if there is any wear on them or where some one might have used a screw driver to push them back on, checking for marks.
Its not the sunroof if you dont have one but check the small plastic panels where your roof rails may go.