You must have "Full Access" or "Limited Access - Website" permissions to delete Layout Containers.
NOTE: Deleting a layout container permanently deletes any page elements inside it. If you are not ready to permanently delete your content, you can adjust the layout container's status to Draft.
Sign in to your site and go to the page with the Layout Container you would like to delete.
On the left-hand side, turn on Edit Mode.
In the right-hand corner of the Layout Container, click on the gear icon.
Choose Delete.
Type 'DELETE' to confirm, then click Delete.