Hi Felicity Thurlow,
I go through the post carefully. you may not delete the notebook in site assets because it is bound to the team site. I would like to know if you choose the wrong class notebook when set up a class notebook in a class teams(for more information: Set up a Class Notebook in Teams using existing content ) if so, there could be not settings to change the notebook that is associated to the default tabs in the class team.
as workaround you may:
- Delete the team and re-create one, this won’t take too long.
- Add a notebook tab in the team that associated to the class notebook.
Really sorry for the inconvenience, I would suggest you give you feedback to the developer of the Class notebook in OneNote UserVoice to let them hear your Voice on the feature. Appreciate your efforts and understanding!
Best Regards,
Clark