I've got a real mental block about how to turn this thing off despite the excellent explanations above.
Once you are in and powered up, if like me you will get the initial display :

Keep pressing the steering wheel Home button until you get to your favourite user set screen.
This will likely take you through the various seat belt displays :

Once there, press this button by your right knee :

This will change the display to this :

In this example the RDMS is the top of the 3 so is already selected.
Now press the rotary button just to the left of the Home button and this should occur :

Now just press the Home button again to get back to your pre-set favourite.
Proper Job
KremSearch (Just a tag to help me find this quickly next time)