Remove billing for a disabled plug-in/add-on feature

I need to stop the billing for the Zoho CRM Plug-in for MS Outlook. I signed up for it in hopes it would be a solution for a problem I had in syncing my Microsoft Outlook Web Access with Zoho CRM. It did not solve my problem, and now I need to stop the billing for the product.

Today I went into Subscription/Manage Users and unchecked the " Zoho CRM Plug-in for MS Outlook " box, then pressed "Save". But I do not see how to stop the monthly billing for the Plug-in. Please direct me to how to stop that billing.

Thank you,

Ken