I have often heard of temptations being described as traps. Traps, at least the actual, physical traps, can be destroyed, but I didn't think that the "temptations as traps" analogy went that far. However, according to Helaman 5:29, the analogy can stretch that far, thanks mostly to another analogy:
Yea, we see that whosoever will may lay hold upon the word of God, which is quick and powerful, which shall divide asunder all the cunning and the snares and the wiles of the devil, . . .(There's more to the verse, but it's not relevant right now.)
I can think of at least one thing that is "quick and powerful" and that "divide[s things] asunder." A sword. And this isn't the first time the word of God has been compared to a sword.
It's not too hard to imagine how a physical sword might destroy a physical trap. Swords can cut through nets and snares fairly easily, and even tougher traps would eventually break if you hit them enough times.
But how does the word of God destroy temptation? Many temptations are built on lies, and the word of God is the truth. Such truths could disprove many of the lies upon which temptations rely, thus destroying those temptations. The word of God can also overpower, if not destroy, temptation by helping us gain a stronger motivation and desire to to good and resist temptation. And if we keep the commandments, we can have God's Spirit with us, and He can help us avoid having to face temptation in the first place.
I think the Word of God destroys temptation the same way we might "destroy" a supposedly logical argument: By disproving its premises, by showing its logic to be faulty, and/or by providing a stronger counterargument. Doing so may not physically destroy temptations because temptations are not actually physical objects, but if we keep the commandments and turn to the word of God in the face of temptation, we can destroy Satan's hopes of getting us to yield to temptation, and that might be good enough.