As others have suggested, it's easy to remove the underline from links. However, if you need to target just this specific link, try giving it a class. Example:
.no-underline:hover {
text-decoration: none;
}
<a href="test.html" class="no-underline">
<div class=" menubox mcolor1">
<h3>go to test page</h3>
</div>
</a>