As for Satan,yes, God could have destroyed him in Eden along with Adam and Eve, but Satan made accusations which God has given time for him to 'prove' - Genesis 3:3-5, Job 2:4. We see the results today on this earth,of the rebelion in Eden. The other angels have been watching so they too can see who's rulership is right. After all,God allowed Satan to rule the earth to 'prove' his charges against God,and for men to try to rule themselves. - John 14:30, Jeremiah 10:23. Incidently,it would be thousands of years before Satan would be cast out of heaven,as he was still permitted to remain and go back and forth during the time of Job,and later, Jesus. It was still to be a future event from when John wrote the book of Revelation around the year 96 C.E. - Revelation 1:10, 12:7-9,12.

I and many others believe Satan and his angels were cast down to the earth,during the early part of the 20th century according to prophetic world events -Matthew 14:7, Revelation 12:10.