First, Welcome.
Second, you're not an idiot. Those things can be a PITA. Sometimes they come off first try, other times, it just doesn't want to come off.
There is a plastic tab that holds it in there. Push down, but better yet, squeez it down to dissconnect the tab. If you look at it, you can see what needs to be done. Once you've done it, it is easier.
Sometimes it is also tough to get the metal spring clip to come off an reengage. It's just tricky.