This I think should be a feature of FlightAware. I have never found a way to delete a photo from FlightAware and I am wondering if there is a way besides creating a discussion on the forum asking for it to be deleted by a staff member.
You can select ‘contact’ from the left pane and open a live support chat during business hours.
Or simply write us an email. Click on “contact” on the left hand side of the page and click on our email address: contact@flightaware.com