Node Hierarchy: Display Children of top most parent in views
You could try adding parent node as a relationship in views, then add a filter and set it to "is empty (NULL)" as a requirement of the field with relationship parent. This will only display nodes that have no parent node set.

If you want to show only nodes whose parents have no parent, you'd add a second relationship (called something like "grandparent") and then set your filter to require the grandparent, rather than the parent, to be empty.