How to rest a Minecraft world

First head to the overview page. Here you can see the name of your world file. If you haven't changed it, it will be called the world.

Then head to the file manager, and delete the file that matches the name set in the overview page.

Want To Keep The World?

If you want to keep your old world, you can change the world name on the overview page, and it will generate a new world with that name. Keeping your old world in the File Manager.

All Done

You're all done, just restart your server.