Zoom Webinar- Go back to "practice session" and Remove all attendees

Once the webinar has started can the panelist/hosts go back to a practice session? When the program is over the panelists like to continue talking privately, but, of course, not in front of the audience. I read that there is something like that in BETA for Zoom Events only. 

Also, can the attendees all be removed from the webinar en masse? 

Thanks!