I have upgraded a website to drupal 8 that I found a field created and I need to delete that field as it became useless.

The field is locked, and this prevents me delete it from the interface.
I tried to delete it using [`field_purge_field()`][1], but it didn't work either.

The answer for http://drupal.stackexchange.com/questions/177156/how-to-properly-delete-fields-programmatically didn't work for me.

**Edit**:
I tried that piece of code but didn't do any thing

    $field = \Drupal::entityManager()->getStorage('field_config')->load($entity_type.$bundle_name.$field_machine_name);
    field_purge_field($field);

How do I delete fields that result locked? How do I unlock them before deleting them?







  [1]: https://api.drupal.org/api/drupal/core%21modules%21field%21field.purge.inc/function/field_purge_field/8.2.x