DEP enrollment utilizes the Automated Device Enrollment to setup devices with Citrix Endpoint Management. Automated Device Enrollment lets organizations configure and manage devices from the moment the devices are removed from the box (in a process known as Auto Advance deployment). You can supervise devices during activation without touching them, and lock MDM enrollment for ongoing management.
For enrolling into Apple Business Manager or Apple School Manager, follow the steps mentioned in the Apple article here – https://support.apple.com/en-us/HT204142
You will find all the steps for DEP enrollment along with screenshots on the Citrix documentation .
Re-enrolling DEP devices
As DEP devices are setup from a factory reset or out of the box condition, we need to follow the same in case of re-enrollment. This means that selective wipe is not the correct way to un-enroll DEP devices. DEP enrollment starts right from when the device is in factory condition which helps to get the devices to supervised status.
For a re-enrollment, we need to perform a full wipe on DEP devices to get it to factory reset condition. Devices under Apple DEP will sync with the Citrix Endpoint Management automatically. After this, a fresh enrollment can be started for the devices.