Mute him next time, or if he continues to piss off other players, start a poll on him.
Since it's his first offense, he gets a warning. But if he continues shittalking like this, he'll get banned.
I can understand that calling germans na
zis is for some people same as calling americans fat or calling welshmen sheepfuckers, but keep in mind it's a stereotype/kind of joke (

) that's both overused and far more harming than the other examples.