Ted here from Shopify, thanks for posting your query.
I'm sorry to hear that you would like to close your store. How was your experience using the Shopify platform? If there's any feedback you could provide I'd be happy to pass this along to the team.
When you close a Shopify account (as mentioned here), this will automatically stop your billing cycle so I'm wondering if there was another account set up accidentally that's still active and is charging you? To help determine this, please click this recovery link and then enter any active email address you have to see if there's another account on file.
If no other account can be found our support can take a closer look into this with you, however, I wouldn't be able to do this here on a public thread such as the Forum Community.
When you have a moment, please contact our live chat, email or callback support here so we can authenticate your details and review those invoices with you. An example of how to contact our support can be found here if you need it. If you no longer have an account with us, please sign in as a guest instead as shown in the video example and our support will help authenticate the account later if needed.
Let me know how this goes and if there is anything else I can help you with, I'm happy to help!