When we put some objects into S3 bucket to verify or validate a CloudFormation stack by uploading a template to S3 bucket, the buckets store thousands of objects that I don't have to keep anymore and we sometimes have to pay too much cost for that after receiving the billing.
Why don't we delete all of the objects and buckets simultaneously or you should consider of using Object Lifecycle Management in advance to automatically delete the objects that has been expired.
* List the buckets you want to remove and input them into a file
* Recursively delete all of the objects, the buckets and confirm that they are deleted
* Use --quiet option if you want to quietly remove