How To Change Status or Delete a Response

From Responses, you can easily change the status of a participant, simply click on the current status inside the participant's status box (for example, click on the word "Paid" or "Confirmed" as shown below). You can then change or update anyone's status from here. 

You can also delete a response from the same place, simply click delete in the bottom right.  

Alternatively, you can delete participants if you check the checkboxes next to any/multiple responses, and then click "delete" from the grey bar that appears at the top of the page.