1. Open «Menu» section.
2. Open "Display Options" (at the top) and check "CSS classes".
3. Open last menu item and enter class name "nospan" (or whatever you want).
4. Add to your style.css:

.nospan span{
display: none;

5. In the template file (header.php or footer.php, etc.) use this code to display menu:
<?php wp_nav_menu('menu=Top Menu&after=<span>|</span>'); ?>
"Top Menu" – is the name of your menu.

#Moosewrap span{
display: none;