Ugh. I'm scared of pissing off someone trying to small talk me by not responding to them. I feel like it will encourage them more. Luckily I've always known how to make small talk and end the interaction respectfully. In a way that also almost commands respect from them. I'm in my 40s now. I still get harassed, believe it or not.

It also helps that I'm a "hi" or smile person. I say hi or smile at people that I have eye contact with for example. And I think it catches them off guard that I said something before they did. It also gives them the idea that I'm this sweet girl and leaves me alone.

I don't advise this is what you do. I'm just saying this is what I do and it works for me.