def METHOD_NAME(filesystem_id: str) -> werkzeug.Response:
    """deleting a single collection from its /col page"""
    source = get_source(filesystem_id)
    try:
        delete_collection(filesystem_id)
    except GpgKeyNotFoundError as e:
        current_app.logger.error("error deleting collection: %s", e)
        abort(500)
    flash(
        Markup(
            "<b>{}</b> {}".format(
                # Translators: Precedes a message confirming the success of an operation.
                escape(gettext("Success!")),
                escape(
                    gettext("The account and data for the source {} have been deleted.").format(
                        source.journalist_designation
                    )
                ),
            )
        ),
        "success",
    )
    return redirect(url_for("main.index"))