I'm guessing it's retained the "on" setting from when you had FSD, but since you no longer have FSD the menu options are now hidden...but the chime is still "on" in software.
I'd further guess this will be painful for you to explain to Tesla because if I'm right they're the only ones who could fix it but they're probably going to misunderstand you several times along the way.
(or I suppose if Tesla still allows 48 hour refund period on software upgrades you could buy FSD on a credit card, turn the switch off, then request a refund- that honestly might be faster than opening a service ticket).