How to delete User, minus sign grayed out? (MacBook pro)

I have deleted guest user accounts before. There are two people who use this iMac. I am the administrator, so I select the padlock, enter my password and I still cannot delete the Guest account by selecting the - sign. There is also a Guest folder displayed unde users. I can drag and drop the folder but can't delete the user via system preferences. Why? and is there another way to delete the guest user. Could the other user have set up the guest user?

If that account’s logged in through Fast User Switching, log it out. If not, select it, click on the padlock at the bottom of the window, and provide your administrator password.

(120349)

That’s a separate setting. Enable the menu and then see what accounts are logged in.

(120354)

No, it won’t.

(120357)

Just asking, but with the lock unlocked, have you highlighted the account you want to delete first?

Hmmm, it's not 10.5.6 you're on then, which version is it?

In your pic, Login items should only be showing for the logged in user, as well as the minus icon only grayed out for logged in users...

So, it seems these accounts are muxed up somehow, at top right of your screen, click on your short name OG & see if more than that account shows a check beside it.

I think we may have to create a new admin account, log out & into that one to see if the same holdup is getting us.

I thought OG was the top admin user, and just to the right of the date/time at the top of the screen you don't see OG?

Here's mine from 10.8.5, can't boot to 10.10 right now... is this even after you made a new admin account?