How Do I Delete A Pretty Plugin Category

Hello,

Not sure why, but when creating categories for plugins, after creating one and then moving to another plugin then when selecting a category, some previously created categories do not appear.

When I create the same category again for the new plugin, then later the category appears twice in the list of plugin categories.

Since this quirk may be a plugin conflict, I am not as concerned about that happening as I am about knowing how to delete categories that are not needed or that happen to get created in duplicate.

Does deleting plugin categories require manually editing the database?

Please advise.

Thanks
Phil D