How to Remove The Default Link Color of The HTML Hyperlink 'A' Tag

How do I remove the default link color of the html hyperlink 'a' tag?

The inherit value:

a { color: inherit; }

… will cause the element to take on the colour of its parent (which is what I think you are looking for).

A live demo follows:

a {
  color: inherit;
}

<p>The default color of the html element is black. The default colour of the body and of a paragraph is inherited. This
  <a href="http://example.com">link</a> would normally take on the default link or visited color, but has been styled to inherit the color from the paragraph.</p>

Is there a way to unset an 'a' tag link to the default color

The value for original setting you're looking for is called initial.

a:hover {
    color: initial
}

However, that might make the link black. Which means it wouldn't work for you in this case. You can get around this another way though, through your a style. Use the inverse of :hover using the :not selector.

a:not(:hover){
  color: #000;
  text-decoration: none;
}

<a href="#">Hi, I'm Link.</a>

Remove blue underline from link

You are not applying text-decoration: none; to an anchor (.boxhead a) but to a span element (.boxhead).

Try this:

.boxhead a {
    color: #FFFFFF;
    text-decoration: none;
}

Remove ALL styling/formatting from hyperlinks

You can simply define a style for links, which would override a:hover, a:visited etc.:

a {
  color: blue;
  text-decoration: none; /* no underline */
}

You can also use the inherit value if you want to use attributes from parent styles instead:

body {
  color: blue;
}
a {
  color: inherit; /* blue colors for links too */
  text-decoration: inherit; /* no underline */
}

Blue and Purple Default links, how to remove?

You need to override the color:

a { color:red } /* Globally */

/* Each state */

a:visited { text-decoration: none; color:red; }
a:hover { text-decoration: none; color:blue; }
a:focus { text-decoration: none; color:yellow; }
a:hover, a:active { text-decoration: none; color:black }