How can I delete an old Prezi account if the email I registered with no longer exists?

I had a Prezi account in high school under s-ashlafer@lwsd.org (this is the account: http://prezi.com/user/e5664q1q7m7v/). Since I graduated, that email account has been deactivated. I would like to delete that Prezi account, but can't because I can't log into my deleted email. How can I delete that Prezi account?