A small point on the post above. The button with the face that is being referred to for device deletion must be pushed for 10 seconds on the phone cradle itself and not on the steering wheel !!

If you dont have a phone cradle fitted in the car then the only other way to delete the device (without taking the car to the dealer) is to attempt to pair an additional 4 BT phones. The BMW system can keep track of 4 phones, so once all 4 are paired, pairing the 5th will overwrite the 1st ... if you see what I mean.

Hope that makes sense ... BMW didn't explain it very well in the phone documentation .... good luck. I bet you are glad you updated your friends s/w now .... ;-)