What do I use to remove the scuff panel fasteners?

[Bombastinator2]

So I’m trying to install a wiring harness for flat 4 lights for a small trailer. Looking at the instructions I am to remove the “scuff panel” (which is apparently the plastic bit at the center bottom of the tailgate). It’s held on by two things in some fairly deep recesses. They feel like (They’re really hard to look at) a circular button with three lobes on The sides. I have no idea how these things work. These are apparently what the “trim tool” is for, but there are apparently a mess of different trim tools and it doesn’t say which one. Though it’s clearly not the one I have. I’m afraid I might break them. How do I do this?