I’m trying to replace the black triangle at the end of the rear windows but I have no idea how to remove it. Anyone know how?

I noticed something weird with the hazard triangle the other night and forgot to post it then. When it gets dark outside and you turn the car off, stare at it. It flashes but not bright enough to catch on camera phone recording. I was sober when I saw this happen. Sent from AutoGuide.com App

want to platic dip the door window trim...got the door trim off with no problem but the small triangle pices at the back of the rear doors...how's that come off???