Can the DNC disallow Biden from running for a second term?

I’ve been having this discussion with a good friend for probably a year. I’ve been saying that the DNC should tell Biden he’s done, he can’t run again, they won’t support him, etc. My friend has been saying “Biden is the head of the Democratic party. If he wants to run again, nobody can stop him.”

After last night’s debate, there is talk of replacing Biden on the ticket, which, of course, may or may not happen. My question is, can it happen if the DNC wanted it to? If they decide that Biden doesn’t have a snowball’s chance in Hell, could they tell him he’s done? I’m not saying that he’s finished or that this will happen, I want to know if it can.