“… that through death He might destroy him who had the power of death, that is, the devil, …” (Hebrews 2:14)
Through His death, Jesus destroyed the devil! That doesn’t mean that the devil no longer exists, but rather than Jesus rendered the devil powerless!
“Having disarmed principalities and powers, He made a public spectacle of them, triumphing over them in it.” (Col. 2:15)
“For this purpose the Son of God was manifested, that He might destroy the works of the devil.” (1Jn. 3:8)
Basically, the devil only has whatever power over us we allow! His primary weapons are lies and deception. Put the devil under your feet (Luke 10:19)! Resist the devil and he will flee from you (James 4:7)!