(30 Jul 2015, 2:59 pm)Michael wrote How do you actually report someone on Flickr?
I have just reported the account, simply go on his account, scroll down to the bottom of the page, click report abuse, select option about stolen photos from the drop down menu, click on the Copyright/IP Policy, then submit a copyright claim.
Edit: Direct Link to Copyright Claim - https://policies.yahoo.com/us/en/yahoo/ip/index.htm