Is there a way to add/edit Smart Content categories?
I tend to use Smart Content way more than the Content Library, but there are some things I'd like to tweak in the category hierarchy, particularly adding subcategories. For instance, adding Prone and Supine subcategories to Poses/By Function/Laying. Really, mostly adding subcategories to Poses/By Function and to Props to make things easier for me to find.
Also, at some point a product with a typo added "Anatomy/Extenal" and I'd like to delete it. Not that it's really hurting anything but it bugs me.
I realize I would have to recategorize things by hand but that's not difficult.

Comments
The Default categories (where the included metadata places the assets) can be deleted, but not renamed or moved (i.e., Read-Only). You can add new sub-categories directly in the Default tree, and they will have full access (Read-Write). For example, you can re-categorize assets into different Default categories, like those in "Anatomy/Extenal", presumably into "Anatomy/External", then delete the offending category. If there is an error in the metadta file itself, stray categories will return if you re-install the faulty product. A help ticket is the only way to get it changed officially. Nothing stopping you from doing it yourself while you wait for some kind of response.
You could make Custom Categories, but that will create a new tree, separate from Default. Some users like to have all Categories in one place.
I have a variety of sub- and sub-sub- categories depending on the type of category I am dealing with that grew over the years. My one major piece of advice is to write it out first and think about it carefully. As new tech has been developed in the real world, I have had to adjust how I think of a category from what it was to what it includes now and can the name be more inclusive. Some of my original names can't be changed on my older computers but can on my newer ones. I am not sure why.
I do this the most in Props and Environments. Wardrobe to a limited degree. And I have been thinking about Poses.
Great, how do I do that? Is it something I can do in the app, or do I have to fiddle with config files?
Oh, I moved the item long ago. I can't even remember which one it was. I just still have that zombie category sitting around.
In the Categories top-level entry, navigate into the Default category tree and right-click on a folder of interest. Delete, Duplicate Category and Create Sub-Category would be of most interest. If you want to delete a folder, make sure it is empty, or at least only contains items you want to delete. Note that Delete means deleting the category and every reference it contains, not the actual assets themselves, they will be safe, if un-categorized, unless you had referenced them in another category.