And no, don't "discuss" this with them.
Telling Nazis not to Nazi isn’t achieving anything. Even the act of telling them off (even yelling at them) is (for them) a confirmation that they’re just having a “political opinion” that deserves at least debating it.
Socially ostracizing them sends a strong signal that they’re not just having an opinion—and they'll have to pick between friends and family or to keep following their criminal cult leaders.