This has been requested before (feature request: In Backlog: Add /ignore functionality to chat (Issue #172) ) but it’s not been implemented yet as the chat has evolved a lot and we haven’t had much issues with the community so far.
We do have an official Code of Conduct policy, and with that a formal process of evaluating incidents case by case basis. Usually the first response is to give the offending user a written warning, but if that doesn’t help, we can also ban users from the site permanently. If the situation is serious we can and will of course help law enforcement with chat logs and other evidence if needed as well.
We’re few weeks/months away from getting rid of the old live page, and after that we have an opportunity to implement more chat commands as well. In the mean time, I suggest you use the mute functionality and if needed, email conduct@slipmat.io and we’ll handle the issue for you.