As an educator you can always hide and delete the sections in Class Material. Hidden materials are shown in light grey.
Hiding a section:
To hide a section, hover over the section name and select the eyeball that says "Hide page". Additionally, you will see an option to hide the page under the "Page options" material
Once a section is hidden it will fade out and not be visible to students. You can always unhide a section by clicking on the eyeball or the page options again.
Deleting a section:
To delete a section just click on the three dots of the relevant section and then click on 'Delete page'.
Remember that by deleting a section it will be permanently gone.