Edit menu html

Hello,

I am trying to edit html of my menu in header, hovewer all the files just got php and refferences and I am unable to find html itself.

The part I would like to edit is following:

<li class=”lang-item lang-item-3 lang-item-sk no-translation menu-item menu-item-type-custom menu-item-object-custom menu-item-2578-sk” id=”menu-item-2578-sk”>

Any clue where could I find this menu html file and edit it ? Also, I would like to add it to wordpress child theme so it won’t change by updates…

The page I need help with: [log in to see the link]