To ignore (you will be the only one not seeing the users messages): either click on their profile picture from the Mobcrush app or their username in chat from the web. You can also ignore from selecting the user in the Viewer List.
To mute (the entire channel will no longer see the users messages): click on the profile picture or username again you have the option of muting a user for 10 minutes, 2 days, or 2 weeks. Please note, that muting will make it to where nobody in the chat can see what the user is saying. You can also mute from the Viewer List.
To ban: click on the profile or username again to bring up the option of banning. You can also ban from the Viewer List. Banning someone removes their messages completely from chat, their name from your Viewers List, and they cannot return unless you then un ban them from your chat list settings. Banning is to be used in extreme circumstances only. Thanks!