On main instrument console centre display. Use the arrows on the steering wheel to move across to settings then arrow down to the parking sensor icon and press the dot button. Lots of other settings in there too.
I had this the other day at traffic lights when I had to squeeze up to car in front because of 'keep clear' box and the beeper started going. I just pushed into 'P' while I waited at the lights. That stops the beeper temporarily.