You can remove any building at any time during or after construction, which results in its destruction and (partial) return of resources. However if you remove a building after “planning” auto-phase but before it actually gets started, hearthlings will still dig out the pit for the foundation.
Steps to reproduce:
- Plan a building and order to start constructing it.
- Wait for the auto-planning phase to finish.
- Pause the game. Ensure there are some hearthlings going to work on it (better turn visible pathing on) but no actions were done yet (no digging and no blocks placed).
- Order to remove the building.
- Unpause the game.
Building removed without trace, hearthlings get reassigned new tasks.
The building plan does get removed, but the digging order does not. Hearthlings will still dig the pit out, although the foundation it is intended for no longer exists.