This post will allow you to disable/prevent MDM/DEP Notifications and macOS POPUPS forcing you to join an organization's MDM. This would be handy if a computer was purchased and not removed from Apple's MDM.
Restart the mac in Recovery Mode Restart your Mac then hold down the Command + R keys together until you're in the Recovery Mode
From the menu bar Click on Utilities then select: Startup Security Utility
A popup appears with 3 choices; select (No security) and restart
NOTE: There is no confirmation notification or button to press
When the system reboots hold down Command + R to get back into Recovery Mode.
Click on Utilities from the top menu bar then select Terminal
In terminal type: mount then press enter/return
A list of devices will show up in a list. You will want to use the volume that specifically says "/Volumes/Macintosh HD"
In my case it is /Volumes/Macintosh HD (/dev/disk3s4)
NOTE: it's not "/" (root), and it's NOT /Volumes/Macintosh HD - Data
In Terminal Write:
- umount /Volumes/Macintosh\ HD
- mkdir /Volumes/Macintosh\ HD
- mount -t apfs -rw /dev/disk3s4 /Volumes/Macintosh\ HD
- cd /Volumes/Macintosh\ HD/System/Library/LaunchAgents
- mkdir xtemp
- mv com.apple.ManagedClientAgent.* xtemp/
- mv com.apple.mdmclient.* xtemp/
- cd ../LaunchDaemons
- mkdir xtemp
- mv com.apple.ManagedClient.* xtemp/
- mv com.apple.mdmclient.* xtemp/
- csrutil authenticated-root disable (this will Turn off Signed System Volume SSV)
- bless --folder /Volumes/Macintosh\ HD/System/Library/CoreServices --bootefi --create-snapshot (this will Save the current disk status in the boot snapshot)
Now you can restart your Mac, and DEP notifications are disabled.
