Why was the Michael Myers storyline removed in Halloween III?

Answer 1

John Carpenter (who was the original owner of the Halloween franchise at the time) wanted to turn the Halloween franchise into an anthology. He wanted to make it a series of stand-alone Halloween-seasoned films. Each one with it's own unique characters, setting, and storyline.

So it would be like this:

Halloween (1978) and Halloween II (1981) were about Michael Myers, an insane criminal who escaped from a insane asylum and goes on a bloody rampage through Haddonfield, Illinios on Halloween night.

Halloween III: Season of the Witch (1982) was about a toymaker who wanted to sacrifice everyone in the world to the pagan sun-god Nuada through Halloween-masks and a television commercial on Halloween night (for those you who still think that Cochran did it for no apparent reason).

And future Halloween films would've told other stories that took place on Halloween night.

Fans of the first two Halloween films were confused by the title and lack of reference to the previous films and as a result the box office suffered and this idea was quickly dropped. And for some it wasn't that Halloween III: Season of the Witch (1982) had nothing to do with the first two films, but the story the producers decided to tell, the fans wanted to something very different from the film, something more traditional. Several years later the idea was brought up to bring back the Michael Myers storyline in Halloween IV: The Return of Michael Myers (1988) officially resurrected the storyline and characters of the original.