Remove blank subheading from matrix

Hello Comunity,

I am having an issue hiding or excluding a blank subheading from my matrix. I have a list of products which have category and subcategory. For some products I have only a subcategory (do not have a subcategory) and I do not wish to have in my matric a blank row shown in the example for the products that do not have subcategory. How can I solve this?

Example in Excel:

Thank you!!