only in patch2:
unchanged:
--- a/core/includes/config.inc
+++ b/core/includes/config.inc
@@ -8,6 +8,7 @@
 use Drupal\Core\Config\FileStorage;
 use Drupal\Core\Config\StorageInterface;
 use Drupal\Core\Config\ExtensionInstallStorageComparer;
+use Drupal\Core\Config\Entity\ConfigStorageController;
 use Symfony\Component\Yaml\Dumper;
 
 /**
@@ -92,6 +93,20 @@ function ($value) use ($name) {
  *   The name of the module or theme to install default configuration for.
  */
 function config_uninstall_default_config($type, $name) {
+  // Handle config entities.
+  if ($type == 'module') {
+    foreach (\Drupal::entityManager()->getDefinitions() as $entity_type => $entity_info) {
+      if ($entity_info['module'] == $name && isset($entity_info['config_prefix']) ) {
+        $ids = config_get_storage_names_with_prefix($entity_info['config_prefix'] . '.');
+        foreach ($ids as &$id) {
+          $id = ConfigStorageController::getIDFromConfigName($id, $entity_info['config_prefix']);
+        }
+        entity_delete_multiple($entity_type, $ids);
+      }
+    }
+  }
+
+  // Simple config.
   $storage = drupal_container()->get('config.storage');
   $config_names = $storage->listAll($name . '.');
   foreach ($config_names as $config_name) {