Here is a pic of one of the joints on my original cage set up so it could be taken off, but it's the same thing you would do if you wanted to shorten it. I can tell you it works fine as a permanent change, but is not a feasible solution if you plan to take it apart very often (like ever). I have a set of 6 sleeves if someone wants to pay shipping they can have them. I replaced mine with hinges.
Good luck...

Good luck...