At the top left corner ("SUM") you can see your current number of guests. If you have activated the distance warning, all guests within the given radius are displayed under "IN". Guests that are outside ("OUT") will be moved up in your list. The number of meters will change from green to red. Guests outside the radius hear a subtle signal through their headphones and are thus informed.
To remove guests from the group, swipe left and tap "Remove."