How to remove default twentytwelve horizontal menu

https://www.jakespharler.com
I am working with a child theme of twenty twelve and think I need to remove the html tags that control the default horizontal menu. I have a vertical menu, so this one is rather redundant. Here are three main questions:
1) To edit the html, should I copy the header.php to my child theme and then just comment out the html tags?
2) Will this cause a conflict with a file from the parent theme?
3) Which html tags should I comment out/remove…the <nav>?

Thanks for your consideration ??