As a "Big Boss" of Tablut Reborn, I messed up a link in Fellowship board 2316 which produced a lot of text which is only visible when I try to edit the description of the board. Editing the board description however is not possible anymore (the "Submit" button has disappeared).

I have reported it as a bug and now I just learned it is not a bug.
I would like to delete the board entirely (looks the simplest solution and I have a back-up) but I don't know how.
So I'd like to know:
How can one delete a fellowship board?