Dealing with a negative search result that won't go away is frustrating, but...

https://wiki-tonic.win/index.php/How_to_Build_Suppression_Content_That_Actually_Ranks:_A_Strategic_Guide_to_SERP_Management

Dealing with a negative search result that won't go away is frustrating, but you aren't powerless. If the publisher refuses to remove the content, focus on technical workarounds instead