I have just won a war against the Mycenaeans, and as I was fighting them, I took their only city and they turned one of their outposts into a new one. In the peace deal I took both. This caused me to be over my city limit, and I want to get rid of the new one that they made. How do I turn cities into outposts or annex a city with another city? Thanks for you for your help in advance.

There is a technology called "Military architecture" in the Medieval Era that allows you merge two cities in exchange for influence.

I hope it helps!!

You can ransack your own cities and districts with one of your Units. They will disapear after this and you can build a new outpost in this area ant link it to your prefered city.