Many have asked the question: Why didn't God destroy Satan at the very beginning of his apostasy and put an end to it once and for all?
I can tell you this: Satan made some accusations about God to the other Angels that were not true. Such as, God is a tyrant. God is mean, and exacting ect...
If God would have destroyed Satan at the inception of his sin,, then all the other angels would have never really known if Satan's accusations were true or not.They would have worshiped God out of fear,,instead of love. So, God has allowed sin to play out so that all may see that God is right and just in His dealing with sin and sinners.
After Jesus was mocked, spit on, slapped, and nailed to a cross the Angels in Heaven no longer have any questions about God and His love for His creation. But, many of us still do. So,, God gives us freewill to choose life,, or death.