First you will need to follow the steps that delete your current world. But do not start your server.
https://www.clanhost.com.au/whmcs/index.php?rp=/knowledgebase/79/Regenerate-World.html
Next you will need to customize you generation settings to your liking. I suggest you backup the file's before editing them.
You can find the files in \Configs Directory.
For example you can edit the file \Configs\WorldGenerator.eco
Save and restart your server. Your server will generate the world with the settings you modified.
