How to make a "Parentless" Page?

Hello, I’m quite new to wordpress and there’s something I can’t do.
I have some child pages I have, but I don’t want all of them displaying on the menu bar everytime someone places the mouse over the parent page, the names are too long and they are a lot of pages, it’s very annoying for everyone. I added the links of the pages on the parent page text anyway, but is there a way so all the child pages stop appearing? Thanks to anyone who answers.