While the meeting is in progress, you can use the security button on the menu bar to restrict participants' access to audio and image.
Zoom - The Security icon in the meeting controls allows the host or co-host of a meeting to enable or disable options during a meeting to secure the meeting and minimize disruption during the meeting.
Lock Meeting: Locks the meeting, keeping new participants from joining the meeting.
Enable Waiting Room: Enables Waiting Room for incoming new participants or to move current participants into the Waiting Room.
Remove Participant: Allows the removal of a participant from a meeting. The participant can not re-join unless Allow removed participants to rejoin is enabled in Meeting Setting.
Suspend Participant Activities: Turn off all participant's video, audio, and ability to share their screen. Also lock the meeting to prevent new participants from joining.
More information: https://support.zoom.us/hc/en-us/articles/360041848151-In-meeting-security-options
Passcode: Meetings and webinars can require passcodes for an added layer of security. https://support.zoom.us/hc/en-us/articles/360033559832-Meeting-and-webinar-passcodes