This response -
chethan177
Nov 13, 2017 12:48 PM
(in response to Taylor E)
Note: This solution might be specific to High Sierra
Try this:
Solution 1:
On startup, click on "Other"
Enter username: root and leave the password empty. Press enter. (Try twice)
If you're able to log in (hurray, you're the admin now), then head over to System Preferences>Users & Groups and create a new Admin account.
Now restart and login to the new Admin Account (you may need a new Apple Id). Once you're logged into this new Admin Id, you can again proceed to your System Preferences>Users & Groups. Open the Lock Icon with your new Admin ID/Password. Assign "Allow user to administer this computer" to your original Apple ID. Restart.
