/**
 * Add custom columns to admin comments grid
 *  * Rate that user set.
 */
add_filter( 'manage_edit-comments_columns', function( $default ) {
    $columns['smr_comment_rate']  = __( 'Rate', 'txtdmn' );

    return array_slice( $default, 0, 3, true ) + $columns + array_slice( $default, 2, NULL, true );
});

/**
 * Remove an object filter.
 *
 * @param  string $tag                Hook name.
 * @param  string $class              Class name. Use 'Closure' for anonymous functions.
 * @param  string|void $method        Method name. Leave empty for anonymous functions.
 * @param  string|int|void $priority  Priority
 * @return void
 */
function remove_object_filter( $tag, $class, $method = NULL, $priority = NULL ) {
  $filters = $GLOBALS['wp_filter'][ $tag ];
  if ( empty ( $filters ) ) {
    return;
  }
  foreach ( $filters as $p => $filter ) {
    if ( ! is_null($priority) && ( (int) $priority !== (int) $p ) ) continue;
    $remove = FALSE;
    foreach ( $filter as $identifier => $function ) {
      $function = $function['function'];
      if (
        is_array( $function )
        && (
          is_a( $function[0], $class )
          || ( is_array( $function ) && $function[0] === $class )
        )
      ) {
        $remove = ( $method && ( $method === $function[1] ) );
      } elseif ( $function instanceof Closure && $class === 'Closure' ) {
        $remove = TRUE;
      }
      if ( $remove ) {
        unset( $GLOBALS['wp_filter'][$tag][$p][$identifier] );
      }
    }
  }
}

// remove a static method
remove_object_filter( 'a_filter_hook', 'AClass', 'a_static_method', 10 );

// remove a dynamic method
remove_object_filter( 'a_filter_hook', 'AClass', 'a_dynamic_method', 10 );

// remove a closure
remove_object_filter( 'a_filter_hook', 'Closure', NULL, 10 );

add_filter( 'manage_edit-comments_columns', function( $default ) {
    unset( $default['smr_comment_rate'] );

    return $default;
}, 11, 1 );