For some reason, you cannot remove your account automatically.
From their FAQ:
How do I delete my account?
Just drop us an email at [email protected], and we’ll make it happen. Send the email from the same email account you used to set up your Zimbio account and include your username. This is to verify you’re the correct account holder. Same goes for changing your username. Send us an email.
Please note that AccountKiller.com is not associated with the business listed on this page. AccountKiller provides easy-to-understand instructions and guides on how to cancel charges and relationships from the list of businesses on our site, we have no affiliation with these businesses.