If you haven't already paid for the policy, you can cancel the order. The title company may charge you for services rendered to this point and if you are in PA, you'll need to sign a strongly worded waiver. PA wants you to know you are totally unprotected without an owner policy.
Now, if you have already paid for the policy you don't have any reason to cancel it. It's a one time charge and it protects you for as long as you have an interest to protect. I would venture to say that title companies don't even have procedures for cancelling owner policies that have already been issued. There'd be no point. ;) The premium has been earned. They insured and they certainly would not issue a refund, so why not just keep the policy?