Node form validates fields with #access = FALSE after ajax image upload
You can use hook_form_alter() to hide the fields so that when the form is rebuilt (with AJAX or normal page load) the fields will still be hidden.

Also if you wanna make a field not validate then use the code below in your hook_form_alter() hook.

function mymodule_form_alter(&amp;$form, &amp;$form_state, $form_id){
  if($form_id == 'your_form_id'){
    // To hide the field
    $form['your_field']['#access'] = false;
    // To remove validation
    $form['your_field']['#required'] = false;
  }
}