When dealing with adult bullies or any other bullies it's best to just ignore them when possible.
Bullies bully people because they are hoping to get a reaction out of the person they are bullying.
So when you react to that bully whether the bully is an adult or a kid, teen etc then you're just fueling the fire so to speak.
The bully will then know that they can get a reaction out of you and know they are hurting you and they get a thrill out of doing so.
So the best thing to do is just walk away from the bully and don't engage them or say anything to them.
However if it still continues then you need to speak up and tell them sternly that you do not put up with their behavior and then if they continue then report them to authorities.
Or get a restraining order against the person that is being a bully.
Or if they tease you about something then laugh about it and say why thank you for your compliment I like "Whatever it is the bully is teasing about".
Eventually the bully will move on and stop bullying you if you do keep ignoring them.