@BlakeRichardson - oh no, that sounds like a huge hassle!
There are some tools Apple has made available to help in this process. The first is "Activation Lock Bypass" - it's available on the device page under Mobile Security. The device does need to be enrolled in DEP and have Supervised settings applied for this to work!
You can also prevent users from logging in with personal icloud/itunes accounts on a device...but usually folks want to allow end users to do this to back up their devices or download personal apps. If you did want to block this, it's under Restrictions> ios restrictions (supervised)> "Allow modifying account settings"
It didn't sound like this was an issue in your case - but like Android, you can also prevent users from factory reseting the device under Restrictions>ios restrictions (supervised)> "Allow Erase All Content and Settings"
Hope that helps in the future!!