Revoke sits in the Share link window, beside the address — a conference, a space, a P2P session, a game. It stops the link working, and it stops nothing else.
The room is untouched
Whoever is already inside stays inside, and anybody who can reach the room another way still can. Only the address dies. A card already sitting in a conversation stops offering a way in, and following the old link from anywhere else says the link is no longer active.
One address per room
Opening the Share link window again shows the address you already have, rather than minting a second one. That is what makes revoking it a whole answer: there is one link to close, not an unknown number of them. After revoking, Share mints a fresh address — so a link pasted in the wrong place is fixable rather than permanent.
Who can revoke
Your own links are yours. A channel operator can also revoke a link that leads into their channel — a conference in it, or its space — because an address people keep arriving through is the channel's business as much as the room itself is.
See also: Sharing a Conference Link · Sharing a Space