Originally Posted by swwhite
Well, it wasn't the case that every single link was immobilized by rust, but the two straight sections were pretty stiff and the whole thing was covered in rust. I had to use WD-40 and some pliers to get the straight parts to bend enough to get them through the little rollers in the derailer. Since a chain replacement is on my maintenance schedule for this spring anyway, I just took the whole thing off. I need the practice, since I am not Mr. Handyman.
Another option might have been to pop the chain into a few pieces with a chain tool to get it off, since you were going to trash the chain anyway.
I've taken some pretty messed up chains, cleaned them and relubed them and put them back into service, including one that didn't bend at all after just a weekend in the garage after a rain-over-salted-roads Friday ride.