IOS – How to you change the iCloud account name on iOS 10

Perhaps you could try addressing the problem from the other side of the issue. When I faced a similar problem with my now defunct student email address on another account, the solution turned out to be contacting the IT department of my old school and convincing them to temporarily re-instate my student email address. Once I convinced them to do it, it turned out to be a really simple process. I was able to change over and recover passwords from several services tied to the old email address, and once completed just had them deactivate it again. Your milage may vary depending on your educational institution, but it's definitely worth a shot.

Under Settings / iCloud you'll see a big red button labeled as Delete Account. Contrary to what it appears, it won't actually delete the account, nor your Apple ID, it will only delete the iCloud's content from your device.

So, to change the device's iCloud account just delete the current one and then log in appropriately.