You can cancel your policy by logging into your account and requesting cancellation. You would have set up login details when you purchased your policy and these can also be found with your cover confirmation documents.
Any return of premium due will be credited back to the credit or debit card with which your purchased the insurance.
We hope this answers your question. For more information or to talk to a professional indemnity adviser please call us on 0345 251 4000 or email support@professionalindemnity.co.uk.