During an active meeting in a space, anyone can select Mute All. Then, everyone except for the person muting and the current presenter, gets muted.
In a standard Webex or Personal Room meeting, only the host can select mute all. Then, everyone except the host and the current presenter, gets muted.
Go to the people list , right-click on anyone's name and select Mute All. Everyone in the meeting sees a notification that lets them know they've been muted, and they can unmute themselves when they need to. They'll also see beside their name in the people list.
To unmute everyone, select Unmute All.