follow Rich's suggestion then fill with distilled water and drive it for a few days. Then drain again.
If the water is still brown, refill with distilled water and drive it for more few days.
When you think it's as clear as you can get it refill with
antifreeze and distilled water.
In North Alabama we use 25%
antifreeze and 75% distilled water. Our low temp. in the winter is 25 degree but the car is inside a garage. We do drive in 35 degree weather but not long.
Dwight