change the color of a link in css while clicked code example

Example 1: how to remove link blue color from a tag using css

a, a:hover, a:focus, a:active {
      text-decoration: none;
      color: inherit;
}

Example 2: css url do not change color of visited links

a {
    text-decoration: none;
}

a:link, a:visited {
    color: blue;
}

a:hover {
    color: red;
}