Hope you´ve received your answer already but if not there were some discussions about cancelling insurance on the forum in the last month or two (sorry can´t find the exact threads). I´m not in CH yet but what I´ve gathered from reading here is that there are only certain times in the year when you can cancel your insurance. I can´t advise you further, sorry, but the answers are here somewhere maybe search for threads that jenny or richard have contributed to.