World's Finest Vol. 1 (1941-1986) #68

Plot

After attempting to destroy an asteroid with traces of Kryptonite, Superman loses his memory. He changes into the clothes in the cape pocket and heads to the Daily Planet. Lois and Perry tell him he is Clark Kent and that Superman has disappeared. When Clark puts on the Superman suit to fool some bank robbers and finds that bullets bounce off him, he credits the suit. He breaks up the asteroid and then decides to reveal to the Daily Planet that though he has been acting as him, he isn't Superman. As he walks to the office, however, he is hit by a truck and remembers that he really is Superman.