So there are a few different ways to go about this. One way is to nest your enemy's code under a "for each" loop. That may be unnecessary if you use functions and instance variables to determine how your enemies act.
As an example of what I mean by my second point, you can do something like:
-If Enemy health =0 -> Call function "Kill enemy" (add a parameter with enemy.UID - the UID is a unique identifying number that belongs only to that instance of teh enemy object)
-On function "Kill enemy"
---Enemy - Pick by UID(function.param(0)) (this is picking the enemy instance using the UID you added to the parameters of the function. In this case it is parameter 0 because it is the first parameter) -> Enemy -> destroy