HI,
I was very clear...
In the Accounts you should have a list on the Left with at least two "accounts" neither of which can be deleted.
The iMessages one and the Bonjour one
Whether the Bonjour one is enabled or not it is always there and cannot be deleted (using in the Minus icon)
The same is true of the iMessages account. Something always shows Whether you have added your Apple ID to the settings or Not.
You can remove the Apple ID (Sign Out).
You can untick the "Enable this Account" box but again you can not highlight it and use the Minus Key.
With the Bonjour Account it has been like this since iChat 1
The iMessages one since Message 7 in Mountain Lion.
Picture from my Test Account (Mac User account) with Nothing set up

Note the minus icon button is greyed out and unusable.

8:30 pm Tuesday; April 7, 2015
iMac 2.5Ghz i5 2011 (Mavericks 10.9)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad