Disable/remove javascript
So it seems like the JavaScript file you are trying to remove is actually coming from a theme. You were also trying to unset array item in non existing variable $js. You could try if this works for you:

function bootstrap_ncr_js_alter(&amp;$javascript) {
  $path = drupal_get_path('theme', 'bootstrap');
  unset($javascript[$path . '/js/bootstrap.js']);
}