add tip about emptying s3 bucket

doc/user/content/self-managed/installation/install-on-aws.md

@@ -515,12 +515,19 @@ kubectl delete namespace materialize-environment
 
 In your Terraform directory, run:
 
+
 ```bash
 terraform destroy
 ```
 
 When prompted, type `yes` to confirm the deletion.
 
+{{< tip>}}
+To delete your S3 bucket, you may need to empty the S3 bucket first.  If the
+`terraform destroy` command fails because the S3 bucket is not empty, empty the
+S3 bucket first and rerun the `terraform destroy` command.
+{{</ tip >}}
+
 ## See also
 
 - [Materialize Kubernetes Operator Helm Chart](/self-managed/)