csrutil disable
Restart computer
In the terminal, type
sudo open /Applications/TextEdit.app /System/Library/LaunchDaemons/com.apple.ManagedClient.enroll.plist
change
<key>com.apple.ManagedClient.enroll</key>
<true/>
to
<key>com.apple.ManagedClient.enroll</key>
<false/>
So that the changes take effect
Look, I bought my MacBook from someone who bought it on eBay. Okay, when I went to format it with cmd + r, I discovered that I was tricked. I spent two weeks looking for how to solve it, until I managed to do it in the way listed above, now I can't sell it because it would give me a headache. Good Luck!