Closing WordPress blog

Hi i want to ask you about how to close my wordpress blog.
I forgot the password and the email that i use for the blog.
I want to close the blog because that blog contains some of private information like email and phone number.
I made that blog with my friends because its a task from our teacher, so we add our information.
But now, after more than 3 years, we just realize that none of us still remember the email and password.
So, please kindly tell me how to close my old blog. Thank you.