title: how do exclude field of method clean form's
body: <p>i necessary remove one field of method clear of my form but he is already declared how required=False. but in the template it has the clean method error if i leave it empty</p>
  
  <pre><code>ship = UnicodeField(max_length=61, label=_('user'), required=False)
  </code></pre>
  
  <p>how do i do to field not show error?</p>