Close my account

Close my account

Hi guys, please, I need to close my account but I can't: when i try, the site gives me this message:

You are an administrator of your organization :  "ZohoNotebook"
You should cancel your organization from  Business , before closing your account.

But I have no idea what it means. How can I do? 
Please, be kind, I'm Italian and don't speak English very well.