You don'tget to remove them. Those aren't screws, they're technically retainers or clips. One time use only. If you're installing factory seat belts, you're probably going to need a special wrench or key for the bolts attaching the belts to the car.
Thanks; will look into the tool.
I must remove them, because I must remove the plate. How do I get them out, and identify what they so I can have replacements before I start taking things apart?
My memory is fuzzy but I think I recall some of those getting in my way in the past. At least you know what you are working with. All I could see at the time was the top and was trying to remove them. I think they might be one time use like Native said but if you are careful you could probably reuse them; that's what I did. It might be worth your time to see if you can find some replacements before you try to remove them. If you have replacements they will be much easier to remove if you don't have to worry about not damaging them.
If you do bust them up go down to the auto parts store and get some new ones. They're pretty inexpensive.