Not everyone online is as nice as Scratch.
There is a zero tolerance policy for harassment of any kind in Kings of Pool, and there are several ways you can combat it.
If someone is being offensive in Kings of Pool chat, you can block their messages by tapping their name and then tapping MUTE. This way, you'll never see a message from that user again.
Beyond that, you should also report them by emailing email@example.com and providing a screenshot and description of the situation.