How do I disable Nether and The End?

Plugins Plugin Development
2

https://docs.spongepowered.org/stable/en/server/getting-started/configuration/sponge-conf.html?highlight=conf

# A list of all detected portal agents used in this world.
        # In order to override, change the target world name to any other valid world.
        # Note: If world is not found, it will fallback to default.
        portal-agents {
            "minecraft:default_nether"=DIM-1
            "minecraft:default_the_end"=DIM1
        }