Satan destroyed?
Hebrews 2:14
Forasmuch then as the children are partakers of flesh and blood, he also himself likewise took part of the same; that through death he might destroy him that had the power of death, that is, the devil
This greek word that is translated as "destroy" is Strong's G2673. It means, to be, or render entirely idle (useless). So, we see that the Devil was not harmed in any way as a spiritual creature. But instead he was bound in some way to prevent him from de-railing or preventing the Church Age. He was idle and useless in preventing the gospel to be preached worldwide.
Satan continues
Revelation 13:3
And I saw one of his heads as it were wounded to death; and his deadly wound was healed: and all the world wondered after the beast.
God now gives us more information concerning how the Devil was being "destroyed" (useless) during the Church Age. Heads are mountains (kingdoms) with their kings (Revelation 17:9-10). Satan's kingdoms are identified as 7 heads in Daniel 7 and in Revelation 12, 13, & 17. We know that this head wounded to death is during the Church Age as per Hebrews 2:14 (above). How do we know this? Look at the next scripture...
Revelation 17:7-8
And the angel said unto me, Wherefore didst thou marvel? I will tell thee the mystery of the woman, and of the beast that carrieth her, which hath the seven heads and ten horns. The beast that thou sawest was, and is not; and shall ascend out of the bottomless pit, and go into perdition: and they that dwell on the earth shall wonder, whose names were not written in the book of life from the foundation of the world, when they behold the beast that was, and is not, and yet is.
This is John speaking in Revelation 17. He is living during the Church Age. Notice how he states, "The beast that thou sawest "... was and is not, and yet is.". How can the beast exist before the Church Age then, simultaneously exist and not exist during the Church Age? Once again we must reference Daniel 7 & Revelation 17:9-10 where we find that the kingdom always needs a king. Satan had 7 earthly kingdoms (heads). But his 6th kingdom head was given a death blow. Satan was denied a physical kingdom to rule here on earth during the Church Age yet he (Satan) still thrived and existed. He was a king without a kingdom.
Conclusion:
Short answer: It was'nt Satan that was destroyed. It was his kingdom.
Satan & his Kingdom
When scripture declares that Jesus "destroyed" the Devil at the Cross (Hebrews 2:14), it was referencing one of the facts that Satan's ability to control an earthly kingdom was halted. Satan could not use another kingdom to stop the progression of the Church Age. Satan himself was not destroyed. The Devil did not cease to exist but instead was cast into the bottomless pit (Revelation 20:1-3). This is why it describes Satan as "...was, and is not, and yet is". He "was" (existed freely) before the Cross, "was not, and yet is" (existed but within the bottomless pit, bound), during the Church Age.
The Beast (Satan without a kingdom) still continued uselessly during the Church Age even though Satan's head was "wounded to death" during the Church Age.