How to deal with asshole customers?

As a shop owner I'm responsible for my workers and also the customers. How do you deal with customers who doesn't respect your workers or anything in your cafe?

Let's be honest catering is one of the hardest jobs ever and you have to deal with people's bullshit all the time with a smile of course.

I'm a barista in my own shop so when I'm working I'm naturally the nicest with everyone even when they're difficult cases but I can't expect the same from my coworkers. They're just working there not actually sold their soul to it.

What do you say to your workers when there's a situation like this? How do you stand up for them? How do you calm them down? How do you dodge a bad unrespectful review? What do you say to the customers? Is there a ban or something in your cafe, or a warning to your people to be careful with someone? What's the worst that happened to you?