@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!
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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!!