CancelReservation
Cancels one of your reservations, by session ID. If you have none for that session, the call returns
404. So a 404 on a retry means it was already gone. You must sign in.
DELETE /v1/events/{eventId}/reservations/{sessionId}
curl -X DELETE -H "Authorization: Bearer $ACCESS_TOKEN" \ https://api.awsevents.com/v1/events/$EVENT_ID/reservations/$SESSION_ID