Basically when you play the game, you defeat ganon only after you completed the main quest, find all memories, defeat the 4 divine beast (insert something else here if i forgot it) then kill ganon, that is the order. But the game being the open world that it is, you can defeat ganon as soon as you get the paraglider and able to reach hyrule castle. Trust me, the story is not worth it, just have fun.