Ban a User from all of your sessions: this immediately removes them from the current world session and they will be unable to re-join the session, or join any session you host, unless you manually revoke the ban. This option can be accessed by navigating to the Contacts page on Dash menu and searching for that user's name. There will be an button to perform this action there. Bans can be revoked in the appropriate tab of the Debug menu (by default accessible with a button on the lower right side of the Dash Home page).