How to dismantle building units

[sampsity]

Does anyone knows how to dismantle building units? its stupid china had 1 million of construction building companies... this is consuming a massive ton of irons. wasting of resources to keep these construction buildings going.

[Andukar]

Just write -100 (for example) when u click on "build".
Simple 100 is +100, but -100 will dismantle unnecessary buildings