jaypro.
You can shorten any chain, o-ring or non o-ring by using a chain breaker. Available at your local shop. (Maybe).
Although, if your chain has stretched that much, you my want to replace it. If it were to break and jam up in the countershaft sprocket it could cost you a lot more than what a new chain would cost. It can also wear out your sprockets.
A way to check it is to grab the chain with your fingers in the middle of the chain where it wraps around the rear sprocket and see if you can lift the chain away from the sprocket. A good chain will cling tightly to the sprocket and a worn chain will lift away from the sprocket. If you can lift it off of the sprocket a 1/2 inch or more, replace it.
Another way is to remove the chain, clean it and lay it out straight on a concrete surface. Take both ends of the chain in your hands and try to push them inward. If you can feel slack or movement in the chain, replace it.
Just my $ .02 :thumb: