At the start of the game, the tutorial gives no option on planning, and its only later you might think about changing the look.

Sorry but demolish and rebuild is the only way,it isn't painful, its something I suspect most of us have done, if you haven't got very far it wont be so disastrous, and if the clutter isn't to your liking,and can't afford to do it all right now, you could do it in stages.

Later on in the game  you might find you want to knock some buildings down in favour of others. 

I forgot,you can demolish all those  on the right side, and most of those on the left, some buildings once built,cannot be demolished and some like infirmary and barracks have to have at least one building remaining,so hard luck if you have put them together,such that you cant have them neatly regulated.