Destroy is a keyword action.
From the Comprehensive Rules:
- 701.6. Destroy
- 701.6a To destroy a permanent, move it from the battlefield to its owner’s graveyard.
- 701.6b The only ways a permanent can be destroyed are as a result of an effect that uses the word "destroy" or as a result of the state-based actions that check for lethal damage (see rule 704.5g) or damage from a source with deathtouch (see rule 704.5h). If a permanent is put into its owner’s graveyard for any other reason, it hasn’t been "destroyed."
- 701.6c A regeneration effect replaces a destruction event. See rule 701.12, "Regenerate."