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
Thank you Mark. Please send me a mail at paul AT paulgodard DOT com as I do not find your email anymore.
Regarding the lost password, I tried the magic trick on safe mode terminal and it work well on my old mac... unfortunately it did not work on the intended mac... impossible to go into safe mode which is a sign that encryption was used. What is extremely frustrating is that before she passed away she wrote the password on a piece of paper but it does not work... so there must be a small mistake somewhere. Do you know a way of using what they have as a seed to generate all possible passwords?