Unlike sessions, group meetings are not streamed to an audience. They are simple calls between members that can include video and/or audio. Every meeting needs a moderator assigned to it. This person could be you or anyone else, that has accepted and invite to the event.
Private meetings can be created by anyone in the event and are only visible to the people included in them. As such you will not see private meetings created by event attendees that do not include you.
If you didn't include yourself in the private meeting you just made, you will not see it show up in the list.
Meetings can be deleted by clicking on the red trashcan icon on the meeting tile.
Private meetings only can be deleted by moderators and the Event Admin
Next: Creating Booths