Hi Prashan,
Please use the online form to fill the data instead of this one.
https://eservices.police.lk/ClearanceCertificate/home.action
In that form, there are 2 questions like below...
Indicate address of High Commission/Embassy/Consulate to which the certificate should be addressed to:
Answer: The Case Officer, Case Processing Centre, Immigration Refugees Citizenship of Canada (IRCC), Canada.
Indicate the address the police clearance certificate should be posted to:
Answer: Your residential address. (They will post you the certificate within 14 working days)