By accident! Don't get all freaked out. It was an accident! The Easton, PA high school put the Hitler quote "And in the last analysis, success is what matters" in its 2010 yearbook, not noticing that it was a Hitlerism.
Which, like, either way, it's kind of an awful quote, isn't it? "Enjoy grownupish life, kids, also: Succeed or die." The Hitlerness of it is just icing on the depressing cake. Anyway, here are some other objectionable Nazi quotes that wind up in yearbooks all the time.
"You don't go to college to meet your husband, you go to meet your bridesmaids!" - Joseph Goebbels
"Wherever you go, go with all your heart" - Hermann Göring
"Dream as if you'll live forever. Live as if you'll die today" - Adolf Eichmann
"True friends stab you in the front" - Eva Braun