Getting rid of unwanted calendars on iPhone

I have mentioned this before somewhere, but I don't think I ever got an answer. When testing and setting up Zulu, I ended up getting a number of redundant duplicate calendars. All these unwanted calendars are listed under calendars in the iPhone's iCal like this.
Does anyone know how to get rid of them. I have oodles of them and wading through them is a pain. Any idea anyone?

Does anyone know how to get rid of them. I have oodles of them and wading through them is a pain. Any idea anyone?