Reset to Vanilla Default World Type
Revert Your Configuration
If you want to go back to Minecraft's default world type selection, open your config file and either delete the world type value or set it to default.
Clear the Setting
Some config formats allow you to leave the field empty or comment out the line entirely. Check your config file's syntax—lines starting with # are usually ignored. Commenting out the world type setting will disable the mod's override.
Restart Minecraft
Save your changes and close Minecraft completely. When you relaunch and create a new world, the world type dropdown should show Minecraft's standard options without any pre-selection.
Verify the Change
Create a test world to confirm the default behavior has been restored. The world type menu should appear neutral, allowing you to freely choose any available type without a pre-selected option.