How to programmatically uncheck 'Generate automatic URL alias' option for all nodes
Figured I'd help out -- took me a while to find it.

Pathauto doesn't implement hook_node_load, so you won't see it there.  My case was I needed to remove an alias in an update hook, and make sure that checkbox is unchecked.

So that's what I did

  $node = node_load(17);
  $node-&gt;path['pathauto'] = FALSE;
  node_save($node);
  pathauto_node_delete($node);
  node_load($node-&gt;nid);