That is not something that can be done by editing an XML file. The XML files generate the options for the theme admin, as well as the widget styles dropdown list. Changing the way the site works can either be done in the theme options ("Shape 5 Theme" on the admin menu), or through widget configuration.
Anything more advanced than what can be done with those methods is likely to require editing actual theme code, which is considered "custom coding" and is not technically covered by support.
However, I believe the change you want to make is fairly simple, so I took a look at the code and I believe the following edit should give you the result that you want:
First: On the "Specific" tab of the theme options, remove all text from the "Menu Text" field.
Next: Locate the following code in the index.php file of the theme (around line #81):
<?php if($s5_pos_custom_1 == "published") { ?>
<!-- Menu and Other -->
<script type="text/javascript">
Finally: Change the first line of that code so it matches this:
<?php if(false && $s5_pos_custom_1 == "published") { ?>
<!-- Menu and Other -->
<script type="text/javascript">
If you change your mind, you can put the menu text back and remove the "false && " from the code.