[Hexonxonx]

Welcome to the forum.
It helps if you put your vehicle details in your profile.
I don't have a tailgate beep, is this some sort of warning that the power gate is in motion?
If so it sounds like a good idea to me.
It could be a legal requirement.

It is a warning when opening closing the power tailgate.
I never once thought it was annoying. I'd never ever consider disabling it. There is a radio talk show guy who helps people with problems like being ripped or injured. One guy called up months ago because he was injured when he rounded the corner of a car when the tailgate was coming down and it caught his head. The OP has tp realize it is that reason why the beep exists.