On the controller, in the Roam’s room, you press on the triangle ‘play’ icon to start playback, which it then turns in to a double line ‘pause’ icon which you would press to ‘stop’ or ‘pause’ playback. Pretty much like any other digital player out there….but you do have to open the controller. 
 

If you’re using some other ‘player’ to send a Bluetooth signal, you’d need to use the controls on that specific player, but it should have similar icons, the triangle ‘play’ and either the double line ‘pause’ or square box ‘stop’, which are interface icons commonly shared across every device/system. 

Thanks Bruce. I kept thinking that the pause button was just a pause, not a stop as well. I guess I was overthinking!

Heh. I do understand that. In the world of Sonos, pause is essentially the same as stop, since it’s just streaming bits, and not actually turning any physical media ;)