SuperFriends (1973) - 7x07 - The Krypton Syndrome- Followmy.tv

Superman travels through a time warp and is taken back to the hours leading up to Krypton's explosion. He saves the planet by stopping the solar flares using the Super-Mobile core and then returns to the present to find Earth a very different place. Robin confronts him and has no idea who Superman is and then remarks that the Justice League was defeated by the Legion of Doom, he is the only one alive. He soon realizes that by saving Krypton that it erased his time on Earth and that nobody had ever heard of Superman before. He goes back into the time warp and makes sure Krypton explodes by removing the Super-Mobile Core because he figures that Earth would need a person like Superman to protect it.