1) Go to "More".

2) Click on "Product/Service Items". 

3) Click on the upper more (3 horizontal lines) icon to have the menu expand. 

4) Slide the category you want to modify to the left. (swipe left) 

5) You will see an "edit" and "delete" button. 

6) Click on "edit". 

7) Make your edits and click save.