How to hide little dash on Header menu

I bought a PHP script from Codecanyon. The link to the script is (https://preview.codecanyon.net/item/atoz-seo-tools-search-engine-optimization-tools/full_screen_preview/12170678).

A dash appears at the top while I’m on the header’s menu. I am trying to change it using text-decoration but it is not working.

When I hover over the menu it shows a blue-colored dash on it. How do I remove it?

I used it
.nav{text-decoration: none !important;}

>Solution :

This blue-colored dash is a border from the top to each anchor tag which was initially set to transparent color, but on hover over any anchor it changes to blue. You can get rid of it by adding the below css property:

.navbar-default .navbar-nav>li>a:hover, .navbar-default .navbar- 
nav>li>a:focus {
  border-color: transparent;
}

P.S: If not works please try using important property, like this

border-color: transparent !important;