It's not possible. Racism is a learned or acquired trait. You aren't born a racist, so unless you want to kill every existing racist so that they can't pass on that ideology to others you'll never eliminate racism entirely. And even if you did kill all the racists on the planet, things happen that make people hateful. Maybe a dude not of your race hits and kills you're friend in a DUI, or whatever, you start hating that guy, then you start hating everybody that looks like him. It's not logical but some people just get hateful. What you need to do online is just stop playing with somebody as soon they start making racial slurs, or whatever you deem racist, it won't change that person, but you won't have listen to that shit either.