Sorry - I figured it out. My account was indeed activated; and I wasn't trying to include a URL, *BUT* I did change my contact email. I had to confirm, and I did.
Here's the deal. I recently lost my domain (royalcomputerworks.com) because either I forgot to check auto-renew at my old provider, or they missed something. (Probably my fault.) In any event, I didn’t want to pay increased prices due to the domain being in redemption status; and I found one I liked better, so I purchased it, pointed it to the server, renamed the account on the server, etc.
However, inside the “Mail” tab in Cpanel, it lists my new account name, as well as one of the old emails for royalcomputerworks.com. When I try to delete the account, it says “Your email account is successfully deleted. Sorry, you don’t have access to that domain”, and the account still shows up.
To clarify, I should point out that I can’t actually log into that ‘account’ – I dunno that it's actually an account so much that it's sort of a glitch - IOW, account may not be actually existing, but still reflected as an account in Cpanel. However, I want it gone; yet I can’t delete it.