What we call races are the phenotype of adaptations of humanity to how and where they live. The idea of races as many people see it in any being, not just humans, is wrong and harmful: for example for dog races it has been shown that pure race animals are much more prone to illness, and mixing races is the best thing you can do.
So in short, we can by any definition say that races do exist, but whatever your definition, the things most people associate with it are not true. So the common idea of people with human distinct races is actually false, such races do not exist. Genetically those races are just different ways we adapt, and it is very random what we call a race and what not.