There is a special tool with a sharp 45 degree angle end that you would slip between the rubber gasket and the chrome trim (very carefully )Before this step though, there is also plastic ,they almost look like popsicle sticks, that you wedge, again very carefully, between the rubber gasket and the trim to find and access your clips.Use two plastic wedge sticks about 2 inches away on either side of your steel retainer to be unclipped and gently open a 1/8th or so gap between the rubber & trim.Then slide your special removal tool into the gap ,snag the side of the clip and gently pull the clip until it comes undone from the mldg.
I`ve been in the resto business about 30 years and still learn new tricks all the time. You`re best advised, if you`re going to try and save a few bucks ,is buy yourself a service manual specifically for your car and it will tell you in the a step by step procedure for just about everything on & in your vehicle. Hope this Helped & Good Luck