Maybe this is already a feature and I'm not aware of it, but I don't see it in the guide. Is it possible to terminate a story thread? On the old CHYOO site, one could choose to create an ending - a thread with no further options. That doesn't seem to be an option on CHYOA these days. Perhaps (and I don't know whether this would be possible), one could indicate a terminated thread by entering the words "The End" into the Follow-Up Question field, and this would remove the "Add a new chapter" option. There are also times when I would like to "lock" a chapter so that no further branches may be added; for instance, I generally prefer that contributors do not add new threads to the Introduction, but instead build off the later chapters. Would it be difficult to add a feature which locks an individual chapter so that no more options may be added to it?
There is currently no functionality to end branches. You can find some suggestions with discussion in the suggestion forum. See here and the links within that suggestion.