I have decided that I no longer need the Pro counters. Can I downgrade? I don't want to delete them, but I don't need all the extras anymore. The only links I see are to upgrade/renew or to cancel.

There is no downgrade option, just let the Pro status run out without renewing. Your account will return to free counter status with 3 free counters available.

But it's automatically renewing each time. How do I stop that from happening?

You really should make yourself familiar with your account. Be that as it may, login to your account and in the upper right hand corner of the main members area page is the Member Information box..it's gray. At the bottom of that box it says 'Pro Purchases' and beside that is a link that says 'View History'.. click on the View History link and set your payment options to whatever you want.