how to disable PVP without enabling cheats

I'm fairly new to minecraft and did some research but they all lead me to editing the server.properties file but I've read on this site that file isn't available for us to edit so how would I disable PVP?

I also want to keep the ability to earn achievements so I don't want to enable cheats since I think that will disable achievements.

Thanks

thank you so much! I figured it would be easy, I just didn't mess around enough to figure it out on my own.