Green’s Dictionary of Slang

to refuse to acknowledge some unpalatable fact or piece of information, to not to be interested in something.

1948		‘Neville Shute’ No Highway (2010) 82: I was trying to tell her what to do if things look bad. But if she doesn’t want to know, I can’t do more .
1959		C. MacInnes Absolute Beginners 57: I was quite polite to your brother, wasn’t I? but he just didn’t want to know.
1965		G. Melly Owning Up (1974) 142: The rest of the band didn’t want to know either.
1975		Bulletin (Sydney) 26 Apr. 45: You wouldn’t want to know, Limp is ravin’ like a’ maniac for 10 minutes and still can’t turn her head.
1998		K. Sampson Awaydays 112: Halifax have talked themselves up over binfuls of ale, but they don’t really want to know.
2002		M. Dorais Don’t Tell: The Sexual Abuse of Boys 40: I don’t want to know. Life’s not worth living in any case. I get by on coke.