If you want to confirm the demolition of a building, you first click on the building you want to demolish, and then click the upgrade button. At this time, you can see a red option and find the destroy button. Clicking it will also ask you to confirm whether to destroy it. Select Yes to demolish the selected building.
Dismantling the building system will give you a certain amount of compensation in the form of returning bottle caps. For example, if you build a building with 120 bottle caps, you will get 60 bottle caps if you dismantle it, and the recycling will be halved.