To change your plan:
Business Control Panel Change Plan Links
See All Available Plans Link
Downgrading: If you choose to downgrade, you may need to remove files and email addresses to avoid exceeding the limits of your new plan. Be sure to save your important files and emails if you decide to downgrade.
Note: If you're an administrator of a Business Mail, Web Hosting or Merchant Solutions plan, you cannot change the owner's plan. However, you can make administrative changes. Learn more about the administrator role.