Remove user field programmatically

use Drupal\field\Entity\FieldStorageConfig;
use Drupal\field\Entity\FieldConfig;

/**
* Implements hook_uninstall().
*/
function mymodule_uninstall($is_syncing) {
 $field_storage = FieldStorageConfig::loadByName('user', 'field_mymodule_notify');
 if ($field_storage) {
   $field_storage->delete();
 }
 $field = FieldConfig::loadByName('user', 'user', 'field_mymodule_notify');
 if ($field) {
   $field->delete();
 }
}