App Data continued

I now have 35 GB of OneNote App Data on my C drive.

I teach visual art and design, so we use class notebooks for keeping photographic records of students work. I'm assuming that the high volume of digital images is whats causing the drain on resources. So we'll have to move to a cloud storage for student work and annotation- maybe Pinterest, which defeats the purpose of having 'all your notes in one place'. Unless its safe to delete all this appdata, using class notebooks for art, design technology, media studies, drama, music- in fact anything that requires students to create hefty digital media content- is un sustainable.

Unless I'm wrong about deleting app data?