Hello, @gwiezdnewrota,
As we have the header builder functionality in our theme, so you can take full advantage of it, you do not need to edit any of the core files.
Simply go to XStore >> Theme Settings >> Header Builder and remove the Logo element from your header and instead use the HTML Block1 element, and add your Logo with the Custom HTML code on your site without an anchor tag and it will work for you.
Regards 8Themes Team.