No. You cannot add new categories, or edit or delete the ones you see in the Cloud Catalog. 

However, you can customize various aspects of these categories under "Settings > Catalog > Categories."Here, you can modify the category specifications, associate categories to specific Phases or Systems, and specify labor and accessories that will be added to all items of the relevant category by default.

If you have products that don't fit into any of the categories listed on Cloud, go to "Catalog > Products" and assign them to the "Uncategorized" category.