Trolls in life must be confronted and not be allowed to get away with it.
It doesn't matter if they are in real life or in real life.
Discussion
The whole point of trolling is to provoke a reaction. Trolls thrive on gaining your time and attention, so by engaging in arguments with them, you're giving them exactly what they want. They don’t care about the substance of the argument; they’re only after the attention. If they succeed in diverting your time—your most valuable resource—from something productive, they’ve won, regardless of whether you "win" the argument or not.