If God is in control, why can't he destroy Satan?
It’s a good question. God could eliminate Satan anytime and plans to do so on his timetable. Until then, we will all struggle and endure Satan’s schemes. As humans, it is our desire to have the one who leads us to temptation removed so we no longer sin or are tempted. However, Satan is not the cause of all evil, pain and suffering. The absence of God’s presence in the hearts of humans allows evil to manifest itself. The good news is that faith in Jesus Christ provides us with the promise of salvation and the strength to resist Satan.
I saw an Angel descending out of Heaven. He carried the key to the Abyss and a chain—a huge chain. He grabbed the Dragon, that old Snake—the very Devil, Satan himself!— chained him up for a thousand years, dumped him into the Abyss, slammed it shut and sealed it tight. No more trouble out of him, deceiving the nations—until the thousand years are up. After that he has to be let loose briefly.
Revelation 20:1-3 (MSG)