You can find it by sending email in following format.
Send E-mail to:
CPC-CTD-Ottawa@cic.gc.ca
Subject: E000xxxx - Visa Office
Body of the mail:
Hello,
I am trying to find out in which Visa office my application is being processed?
Application number: E000xxxx
Date of Birth: 19xx-xx-xx
Last Name: xxx
First Name: xxxx
UCI: -
Category of Immigration: Federal Skilled Worker