Contact Prosura or go to the "Manage Policy" self service link in your confirmation email to cancel your policy. 

Prior to commencement of your Period of Cover, you may cancel your Policy and obtain a refund of the premium paid (Processing Fees will not be refunded).  ...

On and from commencement of the Period of Cover you can still cancel your Policy however a refund of premium will only be available  where you no longer ...

No. Policies may be cancelled via the Self Service Portal or by contacting us.   Policy refund eligibility is assessed in accordance with the Product D...