How can I hide the Organic Groups Audience selection?
You can set #access to FALSE to hide elements like this:


/**
* Implements hook_form_alter()
**/

function yourModule_form_alter(&$form, &$form_state, $form_id) {
  switch ($form_id) {
    case 'yourFormId':
      // We should remove the group check box from users, Its always going to be
      // checked for project content type.
      $form['group_group']['#access'] = FALSE;
      $form['group_access']['#access'] = FALSE;
      break;
    }
}


Above I removed the check box that says "group" and group audience.