Bathing is good, but you can also just drown them, if they're of lesser races. Wikipedia:

 

As president of the American Association for the Study and Prevention of Infant Mortality (AASPIM), Holt promoted reproduction control by society as a means of eugenics. In his 1913 presidential address he said:

We must eliminate the unfit by birth not by death. The race is to be most effectively improved by preventing marriage and reproduction by the unfit, among whom we would class the diseased, the degenerate, the defective, and the criminal.