It's very possible that I'm wrong but I thought they all had caps whether chrome, paint, or black plastic. This is how mine come off, if yours are different then it may still give you a better idea of how to go at it. If you're trying to split the whole thing then you'll pop both mirrors out and there are 5 (I believe) 7mm bolts that come out. Mine has 2 under the big mirror and 3 under the convex.
I pushed the mirror all the way toward the cab and pulled it out with my fingers to make sure I didn't crack it trying to pry with something hard.
I used two small flat heads to release the two clips at the top.
I held the two screwdrivers with one hand while I pulled back the top of the cap with the other.
The other two tabs at the bottom just slide right out.