You really can't say that God created Satan, I think Satan created himself (Yin/Yang) to create a balance between good and evil. What I think is that the snake that told Eve to eat the apple from that tree is Satan or some form of evil that created and Satan was able to take control over it.
I also never said God can't kill Satan, but I think he can't because of the manifestation between good and evil. Even if Satan is evil, he is good in a way by preventing those who committed serious sins from reaping the awards from other people. So in a way Satan is sort of like an antihero.