Hi Cristian,
Thanks for using Meta Box Conditional Logic.
Conditional Logic can works with any DOM element, so you can set the visibility for meta box if page is child or parent. This is some usage example:
Visible when the page is parent (root)
'visible' => array('parent_id', '')
Visible when the page is child
'visible' => array('parent_id', '!=', '')
Visible when the page's parent ID is 99
'visible' => array('parent_id', 99)
Visible in certain page (ID > 101 for example):
'visible' => array('post_ID', '>', 101)
These examples above uses visible action, you can use hidden action in case you want to hide it.
Regards.