We don't currently have a central page where you can see which classes have had room layouts or seating plans created for them.
You would need to click into My Classroom for the lesson to check - you can see how to access My Classroom to check seating plans here: How to open My Classroom
It is also not possible to create, edit or delete seating plans in bulk.
We're always looking for ways we can improve this feature to suit our school's needs. If you have any feedback, please submit it to our product team here: My Classroom