1 Login to the Kinetic Panel and Stop your server.
2 Go to the Settings page
3 Locate the WORLDNAME option and enter a new value.
4 Start the server to generate a new world.
Terraria guide
How To Reset The World On Your Terraria Server
Terraria server owners may wish to reset their server world for a number of reasons, it is possible to generate a new world at any time using the Kinetic Panel.