Make a private room
A room is a board of open invitations for a community, such as a club, a group chat or a course. Members post what they would like to do, and others ask to join. Every request becomes a normal private date.
You get two links: the room link, which you share inside your community, and an admin link that only you keep, to remove posts and manage the room.
Your room is ready
Save the admin link now. It is the only way to manage the room, and it cannot be recovered.
Tell members the passphrase another way, not in the same message as the room link. It cannot be recovered later, but you can set a new one on the admin page.