Roman is still on this forum (as rsh), but I will answer your question for you. The backs do detach. You have to put your finger up where the backs slide onto the rails of the seat itself. You will feel one of two type of releases:
1.) A release that has a prong that needs to be pulled out toward the outside of the chair. You may need a screwdriver to get enough leverage to pry this away if it is tucked up the back some.
2.) A release that gets rotated. This one is easier to deal with but from what I remember was mainly used on the domestic chairs.
If you are by yourself, you can release one side at a time and pry one side up slightly until it releases, then work on the other side and pull the whole back off. Once you do one the rest will be really easy. Good luck.