How to switch off the radio :o/

[Dazbear]

Hello! I bought my Adam last week and LOVE IT (so far)!

This maybe a newbie question..how can I switch the radio off on the infotainment while using Android Auto?

I use Waze as my Sat Nav. I mute the radio, but after a voice direction from Waze the Radio is unmuted again.

So far I have to call a track on Spotify and pause it.

I am sure it may be an obvious solution.......but how can I switch the radio off ;)

Thanks