That sucks! It looks like it is all a bit gummed up, eh.
My guess is that it would take a fix of the plugin to unpick that. And that would take significant time / energy (i.e. money) to do. Of note, there is active work going into it right now, so you might be in luck if you update your site:
Perhaps you could move the topics out of that category and then delete it. You should (hopefully) still be able to navigate to it via /c/football-1/saints-fixtures/34/l/latest to do it via the UI, or you could maybe export / re-import them via the rails console if needed.