I've just had a quick look at the manual. It doesnt mention anything about removing any other items apart from the cam belt.
From your first picture it looks as though the head of the bolt has been rounded, so someone in the past has had difficulty with this bolt as well. and is probably why you think the water pump wasnt replaced when you had the other work done.
So rounded bolt head, combined with lack of room to swing the sledge hammer, I think you're going to have a bit of fun
If you think that removing the red circled part will help i can only suggest that it is bolted through from the front of the block.
sorry i cant be much more help than that