Remove/change drop down menu effects?

Is there a way to remove or change the javascript that creates the hover and submenu effects in the navigation bar? I’d really like to have a simple dropdown menu that just drops downwards when you hover over it instead of a submenu that is animated upwards.

I’m working with a child theme to change css and am wondering if I can use the functions.php file for javascript; I’m unsure how to target only a few lines of javascript instead of an entire file. Any suggestions?