Add a style with the attribute text-decoration:none;:
There are a number of different ways of doing this.
Inline style:
<a href="https://stackoverflow.com/questions/12528316/xxx.html" style="text-decoration:none;">goto this link</a>
Inline stylesheet:
<html>
<head>
<style type="text/css">
a {
text-decoration:none;
}
</style>
</head>
<body>
<a href="https://stackoverflow.com/questions/12528316/xxx.html">goto this link</a>
</body>
</html>
External stylesheet:
<html>
<head>
<link rel="Stylesheet" href="https://stackoverflow.com/questions/12528316/stylesheet.css" />
</head>
<body>
<a href="https://stackoverflow.com/questions/12528316/xxx.html">goto this link</a>
</body>
</html>
stylesheet.css:
a {
text-decoration:none;
}