A. Open the “Product Category” by clicking on the search bar at the top.
B. Add the Category of the product which you want to add as a subcategory.
C. Add the category name in the "category list" column and click on add button.
D. Once added, now that category will appear on the subcategory.
E. Select the subcategory against the selected category.
F. Category and subcategory which you will name it will be appearing here.