You can delete an Event in your account before it starts and before entries have been taken.
Go to your dashboard and click on Total Event.
You will see a list of your existing Events. Click on the red delete button next to the one you want to remove from your account.
Then click Confirm to permanently remove this Event from your account.
Your Event will now be deleted from your account.
Remember, if you want to keep an Event in your account but hide it from public view to stop taking entries, you can Edit your Event and set the Status to 'Inactive' and then Submit your changes. This means the Event will stay in your account but it can only be seen by you.