Hello there!

In my last game I made a range attack on a unit of Stormtrooper composed with only 2 minis: the leader and a medical droid. I had only a LOS on the Leader and after attack and defense I did one wound. I removed the droid is it correct?

Thank you very much!

Almost correct, what your supposed to do in the instance is remove the leader mini, then replace the medical droid with the leader. This causes the leaders position on the board to change which can effect objectives or los for subsequent shots.

Best way to accomplish the swap is to place the speed 1 movement tool against the droid's base, remove the droid, then place the leader model in the spot marked by the movement tool.