Is this possible? Tried holding the selection down and it just rung the out of use number. 

 

You're doing it the wrong way. When in telephone mode select settings - then select user profile - then select manage favourites. You can then press an individual favourite to delete it or you can delete them all at once by using the menu option at the top of the screen. That's how it's done on my Amundsen MIB2 unit. I would imagine it should be similar on the other units too.

Thanks for this