Change/Remove the responsiveness of Navbar

I think you should override parent media queries for the menu in your child-theme style.css

I meant, the media queries of the parent theme css.
You can do what you want, even modify the original files, it’s up to you 😀 Is discouraged ’cause when you update the theme:
a) if you modified the original files in the parent theme, you will lose your changes
b) if you modified copies of the original parent files in your child-theme then you’ll lose possible improvements of the updated parent theme, ’cause they will get overridden.

“ignore” THIS and THAT no, cannot do something of the sort with CSS, you can just override rules.

Hope this clarifies 😀

Override them in your child theme, not remove them from the original theme.
To override mediaqueries (but in general) say there’s a rule, in the parent theme, like:

@media (max-width: 979px){
   some_element { display: none;}
}

you probably want, in your child-theme style.css, something like

@media (max-width: 979px ) and (min-width: 801px){
   some_element { display; block; /*or inline-block, or list-item, or inline, it depends on the element*/}
}

and so on ..
this is enough, because the child style is loaded after the parent style, a rule with the same specificity in the child overrides the one in the parent