..caution::

The ``delete_empty`` option only removes items when the normalized value is

``null``. Ifyour`type`_ is a compound form type, you must either set the

``required`` option to ``false`` or set the ``empty_data`` option to``null``.

Both of these options can be set inside `options`_. See

``null``. Ifthe nested`type`_ is a compound form type, you must either set

the``required`` option to ``false`` or set the ``empty_data`` option to

``null``.Both of these options can be set inside `options`_. See

:ref:`form's empty_data option<reference-form-option-empty-data>` to learn

why this is necessary.