Help, Daughter had a flat

Need to ask a stupid question. My daughter had a flat tire on her 97 Honda Civic, 86,000 miles, 4 cylinder. How do you get the tire/rim off. How does she remove the cener "H" cap in the cener of the rim. She says her owners manual doesn't tell her how. She said there isn't a notch or groove to get the cap off. They removed the lug nuts but the rim won't come off.

Having not seen it, I'm at a loss.

Thanks in advance for your help.