1. Boot to Recovery Mode by holding command-R during restart

2. Open Utilities → Terminal and type

$ csrutil disable
$ reboot

3. Hold command-R during the reboot to enter Recovery Mode again

4. Enter Disk Utility, and mount the Macintosh HD volume (or whatever your main volume is named). (It might already be mounted.)

5. Exit Disk Utility, open Utilities → Terminal, and type

$ cd "/Volumes/Macintosh HD/System/Library"
$ mkdir LaunchDaemons.disabled LaunchAgents.disabled
$ mv LaunchDaemons/com.apple.ManagedClient* LaunchDaemons.disabled/
$ mv LaunchAgents/com.apple.ManagedClient* LaunchAgents.disabled/
$ cd ../../etc
$ echo "0.0.0.0 iprofiles.apple.com" >> hosts
$ echo "0.0.0.0 mdmenrollment.apple.com" >> hosts
$ echo "0.0.0.0 deviceenrollment.apple.com" >> hosts
$ echo "0.0.0.0 gdmf.apple.com" >> hosts
$ csrutil enable
$ reboot

6. When it comes to “Choose your country/location”, make sure to not select a wireless network, but “continue without an internet connection”

7. After a normal boot, you can verify the DEP status in Terminal:

$ profiles status -type enrollment
Enrolled via DEP: No
MDM enrollment: No

You'll get the best results with a full reinstall.

a. Boot into recovery, wipe the harddrive, and select reinstall macOS

b. It will perform installation for approximately 1 hour, and reboot once

c. It will then show a remaining time of appr. 10-15 minutes

d. When it reboots, be sure to press command-R to boot into recovery and proceed with the instructions above.