While Super Friends was being published, DC was wishy-washy about whether it was canon or not (for Earth-One).
But after Super Friends was canceled (and before the Crisis ended Earth-One), I seem to remember that DC came out and said clearly that Super Friends was non-canon. But I can't remember where this was! I thought it was maybe in the letter column in DC Comics Presents #46 or 51, but it's not there.
Does anyone remember where this was said? Or am I mis-remembering, and DC never said it explicitly?
The champion for the opposite point of view was E. Nelson Bridwell, IIRC. And that's a very big "if". But if he said it, he likely said it in The Comic Reader or some similar fan magazine of that era, and probably in an interview. I'd be more vague if I could, but how?