What I usually do is just skim the fat off the top.
It takes a bit of time, but not all that long.
Just take a spoon and remove the layer of fat floating on the water gently.
You can see the glistening fatty layer floating on the more dense water below.
Some folks, when the fat is almost gone, will carefully take some paper towels, and, one sheet at a time, gently absorb the rest by briefly touching the flat towel to the surface of the stock.
Usually do not bother.
Just the way I do it when I am out of time.
Prefer the leave it to cool overnight method.