How to remove the underline for anchors(links)?

Use CSS. this removes underlines from a and u elements:

a, u {
  text-decoration: none;
}

Sometimes you need to override other styles for elements, in which case you can use the !important modifier on your rule:

a {
  text-decoration: none !important;
}

The css is

text-decoration: none;

and

text-decoration: underline;

This will remove your colour as well as the underline that anchor tag exists with

a {
  text-decoration: none;
}

a:hover {
  color: white;
  text-decoration: none;
  cursor: pointer;
}

The simplest option is this:

<a style="text-decoration: none">No underline</a>

Of course, mixing CSS with HTML (i.e. inline CSS) is not a good idea, especially when you are using a tags all over the place.
That's why it's a good idea to add this to a stylesheet instead:

a {
    text-decoration: none;
}

Or even this code in a JS file:

var els = document.getElementsByTagName('a');

for (var el = 0; el < els.length; el++) {
    els[el].style["text-decoration"] = "none";
}