To hide child pages of a parent:

1. In the Dashboard, go to "View Full Dashboard"
2. Pages & Themes > Attributes
3. Scroll all the way down to "Add Attribute"
4. From the dropdown, select checkbox and click "Add"
5. In Handle, enter the following: exclude_subpages_from_nav
6. In Name, enter the following: Exclude Subpages from Nav
7. Click "Add"
8. Now go to "Page Properties" of the parent page
9. Click the "Custom Attributes" tab
10. In the left column, find the new attribute "Exclude Subpages from Nav" that you just added and click on it so it gets crossed out
11. Now scroll back up and check the "Exclude Subpages from Nav" box under the "Selected Attributes" section
12. Click "Save"
13. Now check your autonav, the parent page should appear, but child pages should be hidden.

If you find that this method is not working, make sure that you're using a recent version of view.php in your custom autonav template, because that's where the autonav checks for hidden subpages.

1. You can always grab the latest view.php file at concrete/blocks/autonav/view.php
2. Copy it from there and paste it into your custom autonav template, for example SITEROOT/blocks/autonav/templates/dropdown_menu/view.php

Hope this helps somebody!