The login box at the end is styled slightly different.

Look for:

div#dropMenu li a.noLine {border:none;}

And style accordingly, it looks like you need to put a border around it to make it look like the rest.

If you want the drop down's removed you can find the code in here:

includes/templates/YOUR_TEMPLATE/common/tpl_drop_menu.php

Always back up your files first.

Personally i'd keep it like it is and just change the background of your drop down to something like white.