I believe that trim just snaps on. It covers the screws that secure the skirting to the side wall. I'm not exactly sure of the trick to get it off though. We have the same trim. If I were to try it, I'd probably gently pry the bottom up working my way down the trailer.
John and Rebecca Dickson
Emma-7 / Little John-5 / Iva-1
Full Timing Again, Rev B
2013 Ford F-350 Lariat CC LB PSD
2015 SOB TT - With OC's Awning Poles (#8)
At least in Heaven, RVs will be perfect, and I won't have to keep fixing them.