WP remove all revisioons

wp-delete-revisions.php

<?php
global $wpdb;

if ( check_admin_referer( plugin_basename( __FILE__ ) ) ) {
  $revisions = $wpdb->get_results(
                  "SELECT 'ID' AS revision_id
                  FROM ($wpdb->posts)
                  WHERE 'post_type' = 'revision'
                  ORDER BY 'ID' DESC"
                );
  
  foreach ( $rev as $revision ) {
    wp_delete_post_revision( $rev->revision_id );
  }
}