The 'Report Spam' button is an option you get when you click on someones name in the chat window inside of BDO.

It has been in the game since the very beginning, and it has never worked. There is alot of reasons why this function isn't enabled, which is completely fine and I'm not here to try to get it enabled. I think it's time for this to just be completely removed from the game so we never have to see it again. It's a small thing that doesn't need to exist, and can also confuse new players who think it has functionality.