Answer: A Sara is correct.
Explanation: It's much easier to degrease soup when it is cold. You can scrape the fat of the top or the soup or crack open the fat and pull it away for the liquid. It will not stay attached because fat is water soluble and floats on liquids. And even save this later for a roux. It's much more difficult to degrease soup when it is hot. Unless you skim the top before the soup over boils. Protip: You don't want your soup to boil more than a couple of minutes max. Otherwise you begin to loose complex flavors. Simmer, don't over boil.
Culinary 101
(I'm a Chef)