Board Thread:The Flash discussions/@comment-28109177-20180126033631/@comment-32870856-20180129100351

Ok, for starters, Superman-Prime is not a man, he's SuperBOY-Prime.

Second, he is not from Earth-15, he's from Earth-Prime in the original Pre-Crisis multiverse. He did, however, destroy Earth-15 while trying to find his original Earth (an ultimately fruitless effort).