i saw in the "create new game" menu an option to stop enemys come back when you killed their nests.
Is it possible to archive this in an existing save?
If so, how?

Disable biter expansion
This prevents biters from creating new spawners.
/c game.map_settings.enemy_expansion.enabled = false
Greybeard_LXI wrote:From the Wiki:
Disable biter expansion
This prevents biters from creating new spawners.
/c game.map_settings.enemy_expansion.enabled = false