Yes, it is possible to change auto insurance companies even if you are in mid-policy. Just as you can change parts of your policy during the time that the policy is in effect, you can also decide to make changes to who insures you.
Typically, what is needed to cancel your car insurance policy is a signed form stating your cancellation request.
It would be wise to have your new policy started though before canceling with your current car insurance provider. You may need to show proof of new car insurance with another company for your cancellation to go through.
If you cancel your car insurance policy, the insurance companies we work with will usually send you a check refund if any monies are due back to you. You should check with your current insurance provider to find out if you need to request your refund, if you are entitled to one, or if they will automatically send you a check if you are owed any money after your cancellation.
If you are thinking of changing auto insurance providers, think of CarInsurance.com first. Get a fast, free auto insurance quote here.