Anyone know how to remove these brackets?

I'd like to take off the entire front license plate bracket assembly.
But I've come across these, with welded on nuts:
It looks like I've got to twist them off of their screw, But I'm concerned about scratching the paint underneath.
Is there a rubber washer between the bracket and the bumper to protect the paint?
Or do I need to unscrew the bolt from underneath the bumper?


