What is a 'kill notice', issued by news agencies for Kate Middleton's Mother's Day pic?

A 'kill notice' was issued by major news agencies for Princess of Wales Kate Middleton's Mother's Day photo amid claims that it is manipulated. A 'kill notification" is an industry term used to advise anyone using the photo to remove it from their platforms. The Princess has admitted that the photo was edited and has apologised for "any confusion caused".