Q: Can't disable 'Local Guest' User.

Is Back to my Mac on?

If you have installed Find my iPhone the Guest cannot be romoved.

OOppss  sorry. I see now you have already checked this point.

With both options unchecked, you should not be able to log into the Guest account from the keyboard or remotely for sharing. Are you saying that is still possible with those items deselected?

Even with the options uncheck, the Guest user account will remain in the list. It is just unusable.

Even with the options uncheck, the Guest user account will remain in the list. It is just unusable.

So, can you log into the Guest user?

It says right there on your screen shot that it is Disabled.

It's there cause it's supposed to be.
Are you using file vault?
Your disk is encrypted.
That guest account is for someone who finds your computer to be able to connect it to the internet so that you can find it.