I got hold of a 2010 imac that has the original admin user on it. I set myself as an admin. Is it possible to get rid of the old admin user? The box 'allow user to admin the computer' is greyed out so I can't uncheck it.
Thanks
Absolutely, you can delete the original admin user account now that you've set yourself as an admin. The process is fairly straightforward:
Open System Preferences.
Click Users & Groups.
Click the lock and enter your password to make changes.
Select the old admin account in the list of users.
Click the minus sign below the list of users to remove the account.
The 'allow user to admin this computer' box being greyed out isn't a problem, as you've already established your own admin account.
If you're still having trouble or want to look at this in more detail, I'd recommend checking out this link which provides a step-by-step guide on how to do this.