One way not to associate with that would be to walk away from it, rather than join in.
Trump was pushing back on the journalist’s attempt to paint everyone who opposed tearing down confederate statues as white supremacists. That was wholly reasonable. My Italian American neighbors oppose tearing down statues of Christopher Columbus. Are they Nazis too?
If the way they express their feelings is by joining the Nazis For Christopher Columbus march where the way they express their support for Christopher Columbus is by chanting "Jews will not replace us", that would probably answer the question for us.
Trump was trying to equivocate, to offer support in principle, even though every single one of the people in that rally was actually in the class of people who he was supposedly condemning, and he knew it.
Quite aside from the fact that there is no ethical reason to oppose taking down confederate statues that were erected for explicitly white nationalist reasons:
https://www.npr.org/2017/08/20/544266880/confederate-statues...