Sonos Multi-Room Music System User Manual page 52

Chapter 3: Managing Zones
2. Use the scroll wheel to highlight the zone group you want to change, and press
Drop Zone.
3. Highlight the zone you want to drop from the group, and press OK. The room
that's removed from the zone group stops playing music. The other zones in the
zone group continue unaffected.
You can drop all the ZonePlayers in a group with one touch by selecting All Zones
in Group.
Select zone to drop from group
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