Child pages showing up in menu bar

I am very new to word press and know very little about html. My issue is that I have a bunch of child menus showing up in what I would call the grandparent page’s menu bar. Here’s the Parent page: https://studentaidalliance.org/contact-congress/congressional-social-media/.

As you can see, I have all 50 states and hence, 50 child pages. Having the 50 links in the menu is going to be more than a little bit overkill and it will make the other links there harder to find and use. How do I get rid of them? They also show up in the grandparent page at https://studentaidalliance.org/contact-congress/.

Ideally, I would only have them on the child pages, or not at all. https://studentaidalliance.org/contact-congress/congressional-social-media/alabama/

My theme is Atlantica 2.0.0 by Brandon Jones.

Any ideas/help? I looked at this page https://www.ads-software.com/support/topic/sub-pages-showing-up-in-menu-bar?replies=4 and it was over my head.

I have been told to check wp_list_pages but I have no idea if that is what we use or even how to check it.

Any help would be greatly appreciated.