Dear tcCU,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
I'm sorry to hear that you're having trouble closing your Microsoft 365 account. To completely close your account and remove all information, you can follow these steps:
Sign in to your Microsoft account.
Go to the Billing page.
Select Payment Methods.
Find the credit card you want to remove and select Remove.
Follow the instructions to confirm the removal.
After removing your payment methods or turning off recurring billing you may go ahead and cancel your Microsoft business subscription in the Microsoft 365 admin center.
Once you've completed these steps, your account will be closed, and all information, including your credit card, will be removed. Please note that it may take up some days for your data to be completely deleted from Microsoft's servers.
If the issue persists, you may need to create an official Microsoft support ticket via the M365 admin center so that the billing engineer may use their resources to assist you further. Refer to Get support - Microsoft 365 admin | Microsoft Docs.
I hope this helps! Let me know if you have any other questions or concerns. Please understand that our initial response may not always resolve the issue right away. However, with your help and more detailed information, we can work together to find a solution. Thank you for your help.