1. Navigate to Records> Events and open the appropriate event
  2. Select the Participants tab
  3. Highlight the participant to be deleted
  4. Click Delete from the registrant toolbar
  5. A prompt appears "Are you sure you want to delete this Participant record?" - Click Yes to delete the participant record
Please note: It is not possible to globally delete event participants.  If all participants and event information can be deleted, users can choose to globally delete an event from all constituent records