I canceled my subscription with AWS and did it through a support email to AWS. They answered in about 24hrs and deleted the account.
Here is the correct procedure:
If you would like to cancel your subscription to FileMaker Cloud (5 users), you can do by visiting the "Your Software" page on AWS Marketplace here:
1. Find the title of the software subscription you would like to cancel.
2. Click "Cancel Subscription"
3. A pop-up will ask you to confirm you would like to cancel the subscription. Click "Yes".
Once you cancel, you will no longer be able to start new instances of this software, either from AWS Marketplace or the EC2 console.