kiouii1

I'm trying to set up a creative server for my friends and I, but I don't have any more server slots and I think it's impossible to delete it after you've made one. I tried going into an old one I had and resetting the world and changing the settings, but no matter how many times I do that and save and update and reset blah blah blah none of the changes actually go through to the server when I go into minecraft and try to play on it. What am I doing wrong? It looks so simply but it's not responding to any of my changes, I can't even change the name.