Destroying facilities

Hello,
I recently bought SE5 on steam after a good review in a game magazine I read, and I enjoy it quite a lot.
However I have a problem: I cannot destroy facilities I've already build on a planet.
In example sometimes I want to build a central computer, but I can't because the planet is full, and I cannot find a way to destroy a research facility already on the planet.
I could not find it in the manual, am I blind or is it not possible
Sorry for the n00b question