How to change Server Seed

First Step

Log in to your Wepwawet Control Panel and select your Server

Second Step

Stop your server.

Third Step

Under the General tab, Click on Files, Then select world, world_the_nether and world_the_end and click on the Delete button at the top.

Fourth Step

After that, Click on the server.properties file and go to the line level-seed=[seed] and change [seed] to your prefered seed that you’d like to make your world.

Fifth Step

Click on Save Content or press CTRL+S

Sixth Step

Under General tab, Click on Console and Start the server.