Update a value in a destroy method in Laravel

I make a clone system in Laravel. I want to clone activities.

When I click on "Clone", my line is cloned and receives as the value in the column "parent_id" the ID of the original.

The original gets a value of 1 in the "hasClone" column.

But when I want to delete a clone, in my destroy method, I try to set hasClone (the original entry) to NULL before deleting the clone.

Here is my code :

  public function destroyChanges(Activity $activity)
  {

    $parentActivity = Activity::findOrFail($activity->parent_id)->first();
    $parentActivity->hasClone = NULL;
    $parentActivity->save();

    $activity->delete();

    return redirect()->to('/admin/activity/');
  }

Here is my route :

Route::delete('activity/destroyChanges/{id}', ['as' => 'cancel.activity', 'uses' => 'ActivityCrudController@destroyChanges']);

The entry of the clone is deleted correctly. But he does not update the original entry. How to do ? thank you very much

via Chebli Mohamed