To delete an event on Pelago, edit your event from your event dashboard under My Hosted Events.
If your event is Public, set it as Private so that it no longer appears on Pelago explore screen.
You then need to disable your tickets. To do so click on the Ticket Type from the same screen, your Ticket Type Details screen will appear. Click on "Disable Ticket Type" at the bottom of the screen.
You may then change your event's date to today's date, so your event gets archived tomorrow.