Can I cancel my auto insurance?

I go through American Family and they are killin me. I recently bought a car from a dealership, which of course I had to get full coverage. My rate is now ridiculous and I have found a WAY better rate with a different company so my question is, can I just cancel my insurance? They sent me a bill for $434. I paid half of it today, do I need to pay the other half before I cancel? (Its just hard for me to make two $200 dollar payments for one bill)
I will have to renew my policy in October, and I don’t want to do that. I just don’t want to hurt my credit or receive cancellation fees, so whats the best way to do this?
Refund? Really?

Cancel your current policy (and get the refund for the unused portion) and go with the better deal (as long as it is ACTUALLY a better deal).