title: How to remove registered admin class from menu under Django and xadmin
body: <p>Thanks a lot for your time for reading my questions.</p>
  
  <p>I am using Python 3 / Django 2.0 / xadmin to build my website.
  I have 3 models defined in the model file, such as A, B and C.</p>
  
  <pre><code>class C(models.Model):
      product = models.ForeignKey(A, on_delete=models.CASCADE, verbose_name="TestA")
      product_module = models.ForeignKey(B, on_delete=models.CASCADE, verbose_name="TestB")
  </code></pre>
  
  <p>I would like to add A and B from C's add or update page, but I do not want to have specific menus to handle A and B information in the website.</p>
  
  <p>If I register the model as xadmin class it will bring add function in C's page but new menus for A and B at the same time.</p>
  
  <p>Is there anyway to keep add function but remove the menus?</p>
  
  <p>Thanks a lot for your help and wish you a good day.</p>