Source

File: wp-includes/revision.php

function wp_delete_post_revision( $revision_id ) {
	$revision = wp_get_post_revision( $revision_id );
	if ( ! $revision ) {
		return $revision;
	}

	$delete = wp_delete_post( $revision->ID );
	if ( $delete ) {
		/**
		 * Fires once a post revision has been deleted.
		 *
		 * @since 2.6.0
		 *
		 * @param int     $revision_id Post revision ID.
		 * @param WP_Post $revision    Post revision object.
		 */
		do_action( 'wp_delete_post_revision', $revision->ID, $revision );
	}

	return $delete;
}