I have the same sensors on my Note and Xtrail.

Remove the spare wheel and boot carpet. On the floor will be a wire going to the rear bumper area. Snip it and tape the ends off. Try the sensors they should now be not working. If you need to have them later on, just rejoin the wire and tape off the joint.

It should be fairly obvious which wire it is, as it won't be one of the ones originally there when the car was made. Rear parking sensors are/were a dealer fit option so it' will look a 'bit out of place' compared to all the other ones in the harness. If in doubt consult an auto electrician as it's a two minute fix for him.

If you do cut them make sure you cut each wire individually as your likely to put a short on the system if you blindly cut the cable.

Whats wrong with pulling out the supply plug, removing the fuse will disable other items as I do not think there is a designated fuse just for the reversing sensors