Oh I do beg your parden, but you did not say the idle was such that the aircraft would fly when the throttle was closed only high idle. Also I was not trying to be a smart arse but just giving possible solutions that you may have not known about. I do not know your level of expertise and so I gave the basic answers.
I would assume also that you would have checked the carb for all sorts of problems other than the throttle arm after finding it manually would not shut down the motor.
There was no call label me a smart arse, I just suggested you think about what I said. There are many people who fly with out an electronic kill switch which is a basic safety issue.
Any how I will drag my sorry smart arse off and think of something else to be smart about, but I do hope you can resolve your high idle problem quickly.
Fly safe.