The buzzer on this model does not have an on/off switch. The only way to turn the buzzer off is to disable it.
to the dryer. Remove the rear control panel cover. You will see the buzzer on the left (see image below). Cut the single wire on either side (either wire black or tan) of the buzzer with a pair of side cutters. Tape both of the cut ends of the wire with a small amount of electrical tape.
If you ever decide to use the buzzer again, disconnect power to the dryer and splice the cut wire back together.