Email upgrade Question: removing old domains.

Email upgrade Question: removing old domains.

Hi.
 I'm currently using Zoho's free email service, which is for 1 domain.

 However I'm no longer needing this particular email/domain anymore, as i'm not going ahead with this particular website.

I'm going to be upgrading soon to Zoho's payed email service which allows multiple domains.

My question: Would I be best to just close my free account I currently have (no longer required) and start fresh, or is their a way to delete the main domain so that I can add another? I have looked around the control panel and can't find this option.

Any advice from the admins would be much appreciated.

Thanks, Karl.