I found the solution to this and share it:
find the create.php file in
storefront \ controller \ pages \ account \
and change the following code:
$this->data['form']['fields']['address']['postcode'] = $form->getFieldHtml(
array(
'type' => 'input',
'name' => 'postcode',
'value' => $this->request->post['postcode'],
'required' => ture,
));
Change it for:
$this->data['form']['fields']['address']['postcode'] = $form->getFieldHtml(
array(
'type' => 'input',
'name' => 'postcode',
'value' => $this->request->post['postcode'],
'required' => false,
));
A friend helped me

and I share it with you, I suppose it can be used for something more than the zip code.
