Ask your dealer. They can modify some settings that are not user adjustable. I asked about one such setting and the dealer quoted me a half hour if they could do it. Sadly, the change I wanted was unavailable.
You may also be able to track down the physical speaker making the noise and disconnect it. I remember a 1977 Datsun I bought new, first thing I did. But it was dead easy, I think it took me five minutes. Some sort of obnoxious alert (can't remember now what it alerted, might have been reverse), but probably unlike newer cars, that was all this speaker did - no multifunction.
2018 Kia LX HEV Metal Stream with Advanced Tech