In the Participants page for an event in RE:NXT, you can select several or even all participants and change their attendance, rsvp, or invitation status. However, you can't delete them as participants. If you end up wanting to delete, you have to do one at a time, and since this is required to delete an event, it can be a cumbersome process.
When selecting multiple (or all) participants, 'Delete' should be an option. It would probably be good to have a warning message asking to confirm 'Are you sure you want to delete ## participants from this event?" but you should be able to.
I think I voted for this a while back, but am encountering this again. I thought maybe I could work around the issue by deleting the event itself, but it turns out that can't be done either without deleting all of the participants first and, as far as I can tell, we're still at a point where that can only be done one by one.
Furthermore, participants should be able to be filtered by the constituent lists from which they were imported into the event. This (alongside the deleting-multiple-participants functionality described above) would allow for deleting lists that were accidentally added to an event.
We would be able to filter, select, and delete all participants imported from the accidentally added (or no longer wanted) constituent list.