Let’s appoint this straightforward, this Error “Empty player list given to NetworkServer.Destroy(), nothing to do.” occurs only when a Player shutdown the game immediately. Also, this error cause some of the variable on server synchronizing failure to my game.
i.e. : When a player start the game and exit the game immediately by pressing the “cross” which located at the top-right corner on the Standalone. An error will pops out, which doesn’t cause “lag” to my game. But it cause my Tower keep spawning “Missiles” to this so called (exited Game)Player, in other word meaning its already non existing Player.
For additional information, this tower’s function will working as usual if the Player does not close the game immediately, just like the procedure taken as stated above.
For what I understand, this error occurs because the NetworkServer does not know whether it is to Destroy this player gameobject(Player that shutdown game immediately) or it is not suppose to Destroy. Or maybe I have to destroy using some network function on those player who left from the game?
By that, if anyone of you understand the problem that cause this scenario. Please you are welcome to state it in the Comment below. I thank you. 
[SOLVED]