For information on host controls like locking meetings and managing participants please visit this Zoom page: https://support.zoom.us/hc/en-us/articles/201362603-What-Are-the-Host-Co...
For information on applying a meeting password please visit this Zoom page and scroll down to the bulleted list until you see the word Password: https://support.zoom.us/hc/en-us/articles/201362413-How-Do-I-Schedule-Me...