You’re referring to this verse:
Revelation 9: 11 And they had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath hisname Apollyon.
The King of the locusts is also the ‘angel of the bottomless pit’. To be an angel means to be the messenger of the bottomless pit. Insofar as the pit is concerned, we find that it is Jesus that possesses the key and is the One opening the pit (Revelation 9:1,2,) or closing the pit (Revelation 20:1-3). He is the therefore the Messenger (Angel) of the pit.
The word ‘Abaddon’ as well as the word ‘Apollyon’ point to destruction. Abaddon, Strong’s #3 is a transliteration of the Hebrew word (Strong’s #11) for destruction.
Apollyon is the Greek equivalent. It is Strong’s #623 derived from #622 which means to destroy or perish.
The pit is the place picturing the wrath of God and the place of God’s destruction upon the sinner for their sins. God Himself is the destruction (our God is a consuming fire) that destroys sinners. It is not Satan but God that is the King of destruction. Remember we are told to fear God for this very reason:
Matthew 10: 28 And fear not them which kill the body, but are not able to kill the soul: but rather fear him which is able to destroy both soul and body in hell.
The Bible does not tell us to fear Satan because he can destroy è(#622) us. But it does tell us to fear God for that very reason. God is the King of destruction. Almighty God is the One pictured by Abaddon and Apollyon in Revelation chapter.
Psalms 119:65-72 (KJV) Thou hast dealt well with thy servant, O LORD, according unto thy word.
Teach me good judgment and knowledge: for I have believed thy commandments.
Before I was afflicted I went astray: but now have I kept thy word.
Thou art good, and doest good; teach me thy statutes.
The proud have forged a lie against me: but I will keep thy precepts with my whole heart.
Their heart is as fat as grease; but I delight in thy law.
It is good for me that I have been afflicted; that I might learn thy statutes.
The law of thy mouth is better unto me than thousands of gold and silver.