1 Login to the Kinetic Panel and Stop your server.
2 Go to the Settings
3 Locate the World Name option and change it to a new value`.
4 Start you server to generate a new world.
Valheim guide
How to Reset your Valheim Server World
If you would like to start over on your Valheim server it is possible to easily reset your world by changing the world name at any point using the Kinetic Panel.