KB User's Guide - Documents Tab - Deactivate or Delete a Template
Deactivating or deleting a template will only prevent new documents from being created with that template. It will not have any effect on documents that were previously created.
To find your template, go to the Documents tab and select the New Doc from... link in the left-hand navigation. This will display all of your current templates.
Select the title of the template you wish to deactivate or delete.
To make the template inactive, select the Edit button, set the status to Inactive or Request inactivation (depending on your permissions), then select Submit.
If you had permissions to make the document inactive, and you also wish to delete the template, you may return to the document review screen select the Delete button above the document. Doing this will move the template to the Trash.