Need Help Setting up AI to spawn, move, then despawn

Hey there, i am trying to set up an interaction where the player would walk in to a trigger, which spawns a demon AI behind some trees, and makes it walk across the path that the player is on, and the despawns the AI once the demon has walked behind some trees and is out of sight. I cant seem to find anything to help when i am online. Any help would be much appreciated.