Master of Orion/Obscure Interface Features

Scrapping Missile Bases: Yes, you can do it! Select the planet with too many missile bases. Press 'B' and you will get a slider asking how many bases you'd like to get rid of.

Why? So you don't have to pay maintenance on those bases any more. Useful for planets which are no longer near enemy lines. e.g. after you've wiped out an isolated race.