Delete locked fields, programmatically

Question

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(), but it didn't work either.

The answer for 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?

Answer 1

Purging is the second step, after the field was deleted. field.module should do that automatically for you.

A field config is an entity, you delete it like any other entity:

$field->delete();

Answer 2

Here is this answer, more plainly, tested and working:

\Drupal::entityManager()->getStorage('field_config')->load('my_entity_type.my_bundle.my_field_name');

But remember, the best way to do this, if you can, is simply to delete the field through the UI and then export your configuration using drush cex