WordPress at a glance
function is not described

wp_delete_post_revision() WP 2.6.0

Deletes a revision.

Deletes the row from the posts table corresponding to the specified revision.

Hooks in function
Return

Array/false/WP_Post/WP_Error/null. Null or WP_Error if error, deleted post if success.

Usage

wp_delete_post_revision( $revision_id );
$revision_id(int/WP_Post) (required)
Revision ID or revision object.

Code of wp delete post revision: wp-includes/revision.php VER 5.0.3

<?php
function wp_delete_post_revision( $revision_id ) {
	if ( ! $revision = wp_get_post_revision( $revision_id ) ) {
		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 object|array $revision    Post revision object or array.
		 */
		do_action( 'wp_delete_post_revision', $revision->ID, $revision );
	}

	return $delete;
}