How can a Gravatar exist without a WordPress account?

A few years ago I deleted my WordPress account. Since then, I’ve seen the Gravatar I initially used with it pop up randomly on websites that I access with the email address.
However, when I try to delete the picture, I’m directed to the WordPress site and told that my email doesn’t exist as a user.

I don’t see the sense in having to create a new account to access something linked to the account, which shouldn’t exist.

Is there another way to delete a Gravatar on a nonexistent WordPress account?