Changing Calendars on the iPhone 4

Somehow, I have quite a few Calendars on my iPhone 4. I only want ONE. I was able to delete the extra ones in iCal on my MacBook Pro but don't see a way to delete them on the iPhone 4. Any help will be appreciated. TIA.

You have to do it via Itunes and then sync.

Only one calendar is shown on my iTunes but several calendars are shown on my iPhone 4. ??

Try removing all calendars and then adding them back.