There’re two methods to restarting your world in Minecraft.
Method #1 – Delete World File
To restart your entire Minecraft map without preserving your old world, login to your server via SSH and stop Minecraft. When Minecraft has been stopped, look for your world folder, this should be called world, unless you’ve named it something else. You should also delete any suffixes of your world such asworld_nether. When you’ve done this, simply start Minecraft up, and your world should be automatically generated.
Method #2 – Rename World File
If you’d like to preserve your old world file, but want to start a new one anyway, simply stop your Minecraft server, then open up your server.properties file. Where it says your world’s name, rename that to something else. After you’ve made up a memorable name, simply start Minecraft again. When Minecraft restarts, a new world folder will be created, and anyone that logs into your server will access the new map. If you ever wish to switch back, simply rename the world file back to what it was before.