I’m wondering where it locates or how to open this editor during game. Or there is a mod for that?
As of patch 1.4, released march 2016, there are now mild terraforming tools in the game, no mods or dlc required.
To open them you click the “Landscaping” icon, and the select the terraforming tab. There are a couple of options like raise/lower terrain, level terrain, shift terrain.
Source : Link , Question Author : Steve Reichbach , Answer Author : nickson104