vBulletin uses Cascading Style Sheets (CSS) for the most of the layout, colors, etc. So, you simply have to change a setting in the CSS that is in the Header section of the Admin Control panel.
So, do the following:
1. Log into your Admin Contol Panel
2. Scroll down to "Styles" in the left navigation and select Modify.
3. Select the "[fonts/colors/etc]" for the style you'd like to edit.
4. Search in the "Head Insert" section for:
Code:
A:link, A:visited, A:active {
COLOR: #4274B6;
}
5. Replace with:
Code:
A:link, A:visited, A:active {
COLOR: #4274B6;TEXT-DECORATION: none;
}
6. Click "Save Changes."