What's the best way to clean up user files on a full hard drive?

I have almost 100 laptops that are checked out regularly by any of our 250 students (the one in front of me now has 94 user folders). The trouble is that it's only a 64GB HD, with 57GB after formatting, and 27GB of that is used by Windows. So it only takes 1 ambitous student loading up his OneDrive with Linux ISOs--don't worry: I have already identified him and reined him in--to completely fill up the HD.

So the question is: how do I delete old, inactive user files

We have Microsoft Intune set up for all our machines (the guy before the guy before me set it up though). So I've looked into it and here's our options:

1. Factory Reset
2. Wipe
3. Fresh Start
   
4. Autopilot (which is not set up)
5. Manually delete user folders (which didn't work fully: some folders could not be deleted)
6. Remove user profiles in the Registry (which I'd prefer not to do)

...