A struggle...
For 'categories' I have (uncategorised) for all my posts. Except for my poems, here I use the Tag Cloud in stead of a category, so clicking will gather all poems together on a page. (the other link brings me to a general public page)
By unchecking both marking squares in Edit and Quick Edit, I succeeded in getting a non-linkable (uncategorised) and a linkable (poetry) in my most recent poem. I successively tried to mark all other poem posts likewise, but there (uncategorised) remains linkable. After clicking 'Publish', the check simply jumps back. Probably checking at least one category is an obligation.
Actually I want in the Category survey only 1 category: 'Poetry', but it's impossible to delete 'uncategorised' there because it carries no marking square. But I don't want two different categories in my poetry posts that are both linkable. How do I solve this?