Cancel certficate costs

Regarding the AI recommendation (former answer). for me it's misleading your specific costs. If you are being charged 400 - 430 USD, you are likely paying for an AWS Private CA (Certificate Authority), not just an ACM certificate.

Public certificates are free, but a Private CA costs $400 per month just for existing, even if you aren't using it. Deleting a single certificate will not stop this charge; you must delete the CA itself.

Steps to stop the billing:

1. Identify the Region: Go to your Billing Dashboard -> Bills. Expand the charges to see exactly which Region (e.g., us-east-1) the "Private Certificate Authority" is located in.

2. Navigate to Private CA: Open the AWS Console in that specific region and go to AWS Private Certificate Authority (separate from the standard ACM menu).

3. Disable and Delete:

• Select the Private CA.
• Click Actions > Disable.
• Click Actions > Delete.

Note: There is a mandatory restoration period (minimum 7 days). Set it to 7 days to ensure the resource is permanently removed as soon as possible.

Try to request a Refund: Once the CA is disabled/deleted, open a Billing Support Case

To delete an AWS Certificate Manager (ACM) certificate that you're no longer using, you can use the delete-certificate command with the AWS CLI. The command requires the certificate's Amazon Resource Name (ARN).

Here's the format:

aws acm delete-certificate --certificate-arn arn:aws:acm:region:account:certificate/12345678-1234-1234-1234-123456789012

You'll need to replace the ARN in the command with your specific certificate's ARN.

It's important to note that ACM certificates are actually provided at no additional charge. AWS does not bill you for public SSL/TLS certificates provisioned through ACM. You only pay for the AWS resources (such as Elastic Load Balancers or CloudFront distributions) that you use with these certificates. Therefore, deleting an unused certificate won't reduce your AWS bill, but it's still good practice to remove resources you're not using to keep your account organized.
Sources
Use DeleteCertificate with an AWS SDK or CLI - AWS SDK Code Examples