There could be two different kinds of clips on that trim so don't just start by trying to pry it off. Check inside the trunk and the quarter panel areas inside the car first. There could be snap on clips or studded clips with a nut on the inside or combination of the two. Use a flat putty knife or trim removal tool for popping the trim off the snap on clips. You need to first break the seal on the glass and then just push it out from the inside.
