You are not limited by using standart categories only. Add your personal category with any name and color.
For example, you need a new category, which is not reflected in the results of the breakdown or you need a specific category for your department. You will be assisted by the custom category feature.
open tags menu
scroll down until you see
name your new category and choose any color
Then you can find your new custom category in the breakdown summary section.
At this moment it's not possible to mass delete/edit tags. This feature is in development now. But there's a hint to achieve just that: find all the items and then remove or edit them one by one.