No, there's no way for anyone other than the member to change it. They can change it if they can sign in to the site instead of creating a new account. On any page, at the upper right, they can click on their name, then select Account. It will show the email address they are using. To change it, enter the new one and click on Change Email just below it. They should receive an email to confirm the new one. If they do it this way, they're still associated to any posts, files, etc.
Duane
Duane