Yes, you can cancel your Home Buyer's Insurance policy at any time within the policy term (182 days).
And will I get a refund?
You will only be entitled to a full refund of your premium, if you cancel your policy within 14 days of the purchase date and on the condition that no claims have been made or are pending.
If you cancel your policy after more than 14 days, you won't be entitled to a refund.