How to hide a menu

Hi,

I’m totally new with WordPress and have some very basic questions.
1. I don’t even know the version of WordPress I’m using – where do I find that?
2. I chose the Big Brother theme and want to hide one of the default menus that are in the header. It appears in Hebrew even though I changed the site’s language to English.
Is it something that I do from the control panel or do I have to change html or css files? – and how do I get to those html and css files?

My website address: https://israelimusicsite.wordpress.com

TIA