How do I close our account?

You can try another alternate approach as suggested in this page:

https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/close-account.html#closing-the-account

Please ensure you are logged in as root and not an IAM user. IAM Users do not have the permissions to do this.

1. Review Considerations before you close your AWS account.
2. Sign in as the root user of the account that you want to close, using the email address and password that are associated with the account. If you sign in as an AWS Identity and Access Management (IAM) user or role, you can't close an account.
3. On the navigation bar in the upper-right corner, choose your account name (or alias), and then choose Account.
4. On the Account page, scroll to the end of the page to the Close Account section. Read and ensure that you understand the text next to the check boxes. After you close an AWS account, you can no longer use it to access AWS services.
5. Select the check boxes to accept the terms, and then choose Close Account.
6. In the confirmation box, choose Close Account.