How to add or update a Product Category

How to add or update a Product Category

Under Organization you have Products. When you create products you have an option to add a Product Category.
Currently my options are: Hardware, Software, CRM Applications.

I have searched on how to change this and found this page,
https://help.zoho.com/portal/en/community/topic/how-to-add-a-product-category-%3F
However this refers to Zoho CRM and the instructions are not the same for Zoho Desk.

I have looked in Customize, List of Fields and the Product Category is not in there. I have also looked under modules and there is no option to edit the Products module.

So my question is where do I edit the Product Category options in Zoho Desk?