can i attack a village that is in my Alliance -- when its clearly abandoned and bin used by another Alliance as fridge
You can attack anybody, nothing stopping you from attacking your own team at all.
You might need to handle any consequences if that player returns or if your neighbours don't like your actions of course.
If other kingdoms are attacking a player that is grey in chat then you can usually do it too. Safest thing to do is ask your king or duke about it. Perhaps you guys can organize defense or alternatively kick him out so you can attack freely.