Actually that is not a door buzzer but a key in the ignition buzzer. When you open the door, hey you left your damn keys in the ignition, lol.
I never dug too far as many cars the buzzer is part of the back of the instrument panel. There is a relay panel above the fuse box. I have seen a few buzzers there. It would look like a turn signal flasher but have a round disc on the end that acts as a speaker.
This is how I disabled mine, fairly easy. You'll need a #2 Phillips head and a pair of wire cutters. Remove the center trim cover under the steering column by pulling on it. It snaps into place. Then remove the steering column trim. Two screws underneath hold it on. One screw is obvious and the second screw is kind of hidden beside the white button to return the key back. All you have to do is remove the bottom piece. Look at the key cylinder. You'll see one single black wire going into the cylinder. Cut that wire in two. It is a ground wire where the key completes the circuit for the buzzer. Cut the wire leaving enough room to crimp it back together in the future if you so chose. In other words don't cut it flush with the lock cylinder. Whallah you are done except for putting the trim back on. Just make sure the wire is separated, tape it if you like.
Putting the column trim on don't do like I've done and screw your heart out because you have the left screw in the white button hole and not the screw hole right beside it, lol. Start both screws before you tighten it up.
Lock cylinders occasionally have to be changed. That said if you follow the wire far enough then you might find a connector you can just unplug. I didn't want to spend more time than I had to. The connector might be a foot or two from the key cylinder.
Disclaimer: I'm not responsible for the destruction of personal property, lol.
