You don't need to. You can simply throw away the 1 star director, and place the 3 star director (you said 4 star the second time, but I assume you meant 3 star).
If you were to place the 1 star and then the 3 star, the 1 star would be discarded anyway.
I think you still need to keep 1 star director even it is replaced by 3 star director. It is very important if you have actor chip.