Also, you can't outlaw a "group" because you don't like their message. There's this little thing in your way, it's called the Constitution.
I don't like the Antifa, but as long as they behave themselves (which they almost NEVER do), they have the right to spew their intellectual diarrhea.
You CAN and SHOULD throw people in jail for assault, vandalism, destruction of property, and incitement to riot.