this should have been done before even making the board public, just use a placeholder rather than a value.
Code:
 <div> <div> <input class="textbox default-value" name="vb_login_username" id="navbar_username" size="10" accesskey="u" tabindex="101" placeholder="user name" type="text"><input style="display: none;" class="textbox" tabindex="102" name="vb_login_password" id="navbar_password" size="10" type="password"> <input class="textbox default-value" tabindex="102" name="vb_login_password_hint" id="navbar_password_hint" size="10" placeholder="password" style="display: inline;" type="text"> <input class="loginbutton" tabindex="104" value="Log in" title="Enter your username and password in the boxes provided to login, or click the 'register' button to create a profile for yourself." accesskey="s" type="submit"> </div> </div>
please replace it with this!