According to Z8Games "Top 10 FAQs"
How to change my E-mail
You can change this information by sending your account ID, security question / security answer to Z8Games - Support
4. I forgot the answer to my security question.
The only way to retrieve the answer to your security question is to submit a support ticket containing all the information you entered during the registration process, in addition to your registered email address. This is in order to verify your identity. Be warned, the process of retrieving the answer to your security question can take time.
As far as I can tell the E-Mail and Security Question is tied together this is put in place to prevent Scamming accounts. If there were a way to change the E-mail without a Security Question you could easily steal any account you have the ID and password to.
Maybe someone knows a way that I do not, But I highly recommend you simply Contact Z8games support with any information possible (Including your IP address) to get your Security Answer, and if you are attempting to steal an account I encourage you not to.