AWS CloudFormation launches a new parameter called DeletionMode for the DeleteStack API. This new parameter allows customers to safely delete their CloudFormation stacks that are in DELETE_FAILED state.
Today, customers create, update, delete, and re-create CloudFormation stacks when iterating on their cloud infrastructure in their dev-test environments. Customers can use the DeleteStack CloudFormation API to successfully delete their stacks and stack resources. However, certain stack resources can prevent the DeleteStack API to successfully complete for e.g. when customers attempt to delete non-empty Amazon S3 buckets. The DeleteStack API can enter into the DELETE_FAILED state in such scenarios. With this launch, customers can pass FORCE_DELETE_STACK value to the new DeletionMode parameter and delete such stacks.
Source:: Amazon AWS