diff -u b/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php b/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php
--- b/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityStorageBase.php
@@ -465,6 +465,8 @@
         $translation = $entity->original->getTranslation($removed_langcode);
         $fields = $translation->getTranslatableFields();
         foreach ($fields as $name => $items) {
+          // Call the delete method with the parameter $parent_delete set to
+          // FALSE to indicate that only an entity translation is being removed.
           $items->delete(FALSE);
         }
       }
reverted:
--- b/core/lib/Drupal/Core/Field/FieldItemInterface.php
+++ a/core/lib/Drupal/Core/Field/FieldItemInterface.php
@@ -217,13 +217,8 @@
    *
    * This method is called during the process of deleting an entity, just before
    * values are deleted from storage.
-   *
-   * @param bool $parent_delete
-   *   Specifies whether the whole parent is being deleted or only a
-   *   translation of it. TRUE if the whole parent is being deleted, FALSE if
-   *   only a translation is being deleted. Defaults to TRUE.
    */
+  public function delete();
-  public function delete($parent_delete = TRUE);
 
   /**
    * Defines custom revision delete behavior for field values.
reverted:
--- b/core/lib/Drupal/Core/Field/FieldItemListInterface.php
+++ a/core/lib/Drupal/Core/Field/FieldItemListInterface.php
@@ -156,13 +156,8 @@
    *
    * This method is called during the process of deleting an entity, just before
    * values are deleted from storage.
-   *
-   * @param bool $parent_delete
-   *   Specifies whether the whole parent is being deleted or only a
-   *   translation of it. TRUE if the whole parent is being deleted, FALSE if
-   *   only a translation is being deleted. Defaults to TRUE.
    */
+  public function delete();
-  public function delete($parent_delete = TRUE);
 
   /**
    * Defines custom revision delete behavior for field values.
diff -u b/core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/FieldTestItem.php b/core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/FieldTestItem.php
--- b/core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/FieldTestItem.php
+++ b/core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/FieldTestItem.php
@@ -114,9 +114,9 @@
    * {@inheritdoc}
    */
   public function delete($parent_delete = TRUE) {
-    parent::delete();
+    parent::delete($parent_delete);
     $deleted_languages = \Drupal::state()->get('entity_test.delete.' . $this->getFieldDefinition()->getName()) ?: [];
-    $deleted_languages[] = $this->getLangcode();
+    $deleted_languages[$this->getLangcode()] = $parent_delete;
     \Drupal::state()->set('entity_test.delete.' . $this->getFieldDefinition()->getName(), $deleted_languages);
   }
 
only in patch2:
unchanged:
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php
@@ -904,11 +904,17 @@ public function testDeleteEntityTranslation() {
 
     // Ensure that for the translatable test field the second and third
     // langcodes are in the deleted languages list.
-    $actual = \Drupal::state()->get('entity_test.delete.translatable_test_field');
-    $expected_translatable = ['l1', 'l2'];
+    $deleted_information = \Drupal::state()->get('entity_test.delete.translatable_test_field');
+    $actual = array_keys($deleted_information);
+    $expected_translatable = $removed_languages  = ['l1', 'l2'];
     sort($actual);
     sort($expected_translatable);
     $this->assertEqual($actual, $expected_translatable);
+    // Ensure that the delete method was provided with the correct information
+    // that only an entity translation is being removed.
+    foreach ($removed_languages as $langcode) {
+      $this->assertFalse($deleted_information[$langcode]);
+    }
     // Ensure that the untranslatable test field is untouched.
     $this->assertNull(\Drupal::state()->get('entity_test.delete.untranslatable_test_field'));
 
@@ -916,16 +922,23 @@ public function testDeleteEntityTranslation() {
     $entity->delete();
 
     // All languages have been deleted now.
-    $actual = \Drupal::state()->get('entity_test.delete.translatable_test_field');
-    $expected_translatable[] = 'en';
-    $expected_translatable[] = 'l0';
+    $deleted_information = \Drupal::state()->get('entity_test.delete.translatable_test_field');
+    $actual = array_keys($deleted_information);
+    $entity_left_translations_before_deletion = ['en', 'l0'];
+    $expected_translatable = array_merge($expected_translatable, $entity_left_translations_before_deletion);
     sort($actual);
     sort($expected_translatable);
     $this->assertEqual($actual, $expected_translatable);
+    // Ensure that the delete method was provided with the correct information
+    // that the entity is being deleted.
+    foreach ($entity_left_translations_before_deletion as $langcode) {
+      $this->assertTrue($deleted_information[$langcode]);
+    }
 
     // The untranslatable field is shared and only deleted once, for the
     // default langcode.
     $actual = \Drupal::state()->get('entity_test.delete.untranslatable_test_field');
+    $actual = array_keys($actual);
     $expected_untranslatable = ['en'];
     sort($actual);
     sort($expected_untranslatable);