タスク定義のリビジョンを削除できるようになっていた 今まではactiveかinactiveしかなかったけれど
If you decide that you no longer need a specific task definition revision in Amazon ECS, you can deelete the task definition revision so that it no longer displays in your ListTaskDefinitions API calls or in the console when you want to run a task or update a service. When you delete a task definition revision, it immediately transitions from the INACTIVE to DELETE_IN_PROGRESS. Existing tasks and services that reference a DELETE_IN_PROGRESS task definition revision continue to run without disruption. You can't use a DELETE_IN_PROGRESS task definition revision to run new tasks or create new services. You also can't update an existing service to reference a DELETE_IN_PROGRESS task definition revision.
