Back up your iPhone
Update iPhone to the latest iOS version
On a Mac, open Apple Configurator
On Windows, install Apple Devices or iTunes if required
Connect the iPhone to the computer with a USB cable
Trust the computer on the iPhone if prompted
In Apple Configurator, select the iPhone
Choose Prepare
Select Manual Configuration
Check Supervise devices
Check Allow devices to pair with other computers only if needed
Sign in with an Apple ID if required
Complete the setup process
Erase and reconfigure the iPhone if supervision is applied during setup
Verify supervision in Settings
Check General
Check About
Look for Supervision or Managed status
Use an MDM solution if you need ongoing management
Enroll the supervised iPhone in your MDM server
Keep the supervision identity and recovery information secure