Do you have a picture? Is that where the speakers Are? It will probably void the warranty.
Here is a site that explains how to paint your tv frame.
To to the craft store n get some black tape. If you do cover the speaker you can carefully poke holes in tape. Tired of it ? Just pull tape off. Just curious as to why ? Me, I'm kinda eccentric lol, I made a frame for my tv from a picture frame because the color of the tv distracted me in the room , didn't match n stood out. Then my daughter hi jacked it .