You can get chrome metal tape at Pep Boys etc. When I did the same years ago, I cut out a circle of it just larger than the hole. Taped that over it, it conforms to the round support and is barely noticeable.
I like the gaurd for looks & function. To me it looks like something missing without them, & cheaper with out unless it's a all out custom show bike.
Imagine all the money Moco made from not installing them, in sales of bags afterwards.
This would be an excellent time to bolt your bags in place and get rid of the split pin spring clip thingy. With those guards gone there is nothing to catch your bag when the thingy fails.