A container represents a data storage location holding the data to be featurized and registered with Data Explorer. A container can be an S3 bucket, Azure blob store, Google Cloud Storage bucket, or a directory on the local file system. The container is registered through the web portal UI, with the user providing the details like the endpoint URL, credentials, etc.
If all your data is present on a file system accessible to adectl, then explicit container registration is not required. Data registered from the local file system will not have a few web portal capabilities like viewing of full-resolution images, previewing contents when creating a dataset, etc.
The Containers page is available under 'Data -> Repo'
The Containers page is displayed with the options as seen in the below image:
If a container has an associated Dataset, then the Delete option to delete the container will be disabled.