I don't think you'll get an answer from Intuit about this because this is not an actual service, more of a community of users help forum. I think Intuit may chime in about a specific serious issue, but probably not your request.
If you want to cancel some online tax preparation service, you should check the account for that service for a link that will get you customer support. But if you don't want to receive emails from this website, you can check into your profile preferences and uncheck boxes that say you want to receive emails.
If you already filed and the fees were suppose to come out of your refund then it is too late to cancel. And they do not refund the Online versions. You don't have to pay until you want to print or file. Once your return is filed you can not cancel it.