Hard question of what to do in the moment.
Mostly it is to not seem like a target.
Walk confidently. Be a leader. Be smart. Have your wits about you.
Even if you do not want to fight, be ready to fight.
Stand up straight.
But other situations call for diffusion. If a little kid was yelling at you, you would not feel threatened. Treat a bully like that.
But be able and ready to defend yourself. And back away after as law requires.
Leave if you can.
The best win is not to get in a fight.
What if they insult your wife, mother, brother, father, dog, cat, etc.? You can still de-escalate.
Just keep repeating you should leave man. You are just looking for drama and you are not going to find it here. Keep walking.
Take charge of your group and say you are leaving.
There is no winning fighting in the street. If you train martial arts, you do it so you can have calm. You can deescalate the fight.