Open the world creation menu in Dregora
Select the world type or preset options
Choose a flat world preset if available
Set terrain generation to flat or superflat
Disable biome variation if the option exists
Turn off structures if you want a completely flat setup
Adjust layers to use only the blocks you want
Save the preset or world settings
Create the world with those settings
If Dregora does not support superflat directly, use a custom world preset or datapack that forces flat terrain