[Gary King]

It's in the admin/template.php

Find

PHP Code:

  $only['showgroup'] = 'Show Groups'; 


and below that, add the following (replace the CAPS with your own values)

PHP Code:

$only['PREFIX_OF_TEMPLATES']="NAME OF TEMPLATE GROUP"; 


Then, you'll have to change the templatesetid value in the database in the template table, to -1 (this will move it in the template group, BUT will also make this a global variable, meaning that it appears in all template sets!)