How do I destroy a building ?

You want to destroy a building that does not fit anymore in your development strategy ? Nothing more easy. Here's, for instance, how you need to proceed to destroy a level 22 selenium mine, taking it down to level 21 :

Select the “destroy” button. The operation will cost you 743k of rhenium and 371k of selenium to destroy level 22. The destruction will take 2hours 20 minutes and 26 secodnds.

ATTENTION : You will loose the amount of point the building has given you.