Sometimes objects stand in the way of the construction work or some old infrastructure should be demolished. There are several ways to remove these objects.
In any case, if the removed object has changed the terrain, the terrain is restored as much as possible to the state it was in before the removed object was built.
Everything in the game world - except industries and the headquarters building - can be removed by bulldozing. Objects which can be bulldozed are highlighted in yellow while they’re hovered in the bulldozer mode. If a construction, like stations or depots, is to be demolished, a confirmation is required before it is actually removed. Holding SHIFT while clicking on a construction will skip the confirmation. To remove several assets without confirmation, you can hold down the left mouse button and drag the mouse.
When streets in towns are demolished, the adjacent town buildings, bus/truck stops and waypoints get removed as well. They can be removed individually by clicking on them instead of the street. The same applies to tracks with signals and waypoints.
It is possible to build over existing objects to remove them if they collide. This works for anything that does not require a confirmation as explained above. When you upgrade streets so that they change in width and no longer fit the town buildings, these town buildings are bulldozed automatically if necessary. The bulldozing cost is added to the building/upgrade costs.
Landscape assets like trees and rocks can be removed with the eraser tool. You can drag the tool to clear a path of assets. There are several parameters available to adjust the size, form and sensibility of the eraser tool.