I will just add that regardless of what the law says concerning privacy in public places, there are circumstances and situations where people have personal and private reasons why they don't want their photographs taken. I don't know what prompted OP's supposed subject to ask for removal of the photograph. Some of them are truly sad situations and the fear is real.
But if someone asks me to delete mine, I'll try to honor their requests. No, I will not tell them they should stay home. In these cases, in my mind, their needs superceeds my rights. I don't ask for details either. Using film makes it little more difficult but in digital, removal is easy.
I will not explain why I think this way or what I know, so please don't ask.