how do I get rid of them?
If you disable MDM enrollment it should solve your issue. In order to do that you have to be an Administrator on the machine.
Using the GP editor, the path is Computer configuration > Administrative Templates > Windows Components > MDM > Disable MDM Enrollment.
You can find the registry key here:
Update: After a reboot, realtime protection came back on... So this answer does not work for me. But since it proposes a new method (the registry edit) I'm leaving it here. It could help someone else. Different people seem to have success with different methods.
I also find that updating to 21H1 does not help.
For me, it was very difficult to disable ...