I've made this guide on how to remove the aerial on the seicento.

Hope this comes in handy (y)

Step 1 :

Flick out interior light and completely disconnect and remove it.


Step 2 :

Then unscrew and remove both rear view mirror.

2 gold screws holding the roof lining then the 3 black holding the mirror.
Once you've done this wiggle and pull it out and pull out the pieces of sponge
that go either side of the mirror and put these to one side.