Make Enemies disappear?

[Schinki]

Hello guys, first of all: I'm sorry if my English is bad

I just started to create my first little Custom Story and I have already looked up for a script to spawn an enemy if you step on a script area. Now I want to go back, let the enemy step on another script area and make him disappear. Right now it looks like this:
"void OnStart()
{
AddEntityCollideCallback("Player" , "Schreck" , "MonsterFunc1" , true , 1);
}
void MonsterFunc1(string &in asParent , string &in asChild , int alState)
{
SetEntityActive("Monster1" , true);
}"

Could anyone please complete this script for me? I would be very thankful.