Delete a running cluster.

def delete(self):
        """Delete a running cluster."""
        stacks = [
            self.utilities_name,
            self.spot_nodes_name,
            self.node_group_name,
            self.cluster_name,
            self.vpc_name,
            self.role_name
        ]
        # Execute creation.
        for stack in tqdm.tqdm(stacks, ncols=70):
            self.delete_stack(stack)