You can access ECS functions under the AWS Services menu, selecting the Elastic Container Service link.
If this is your first time logging in, you must go through a tutorial, where you will be forced to create a sample app. I would recommend going through the tutorial and deleting your sample app afterward. In order to delete a service, you'll need to update your service's number of tasks to 0. In addition, delete the default cluster to avoid any unforeseen charges.