Destroying/killing an effect prefab?

hey,

i'm spawning a smoke prefab with Effect.server.Run("assets/bundled/prefabs/fx/smoke/generator_smoke.prefab", airplane.transform.position, Vector3.up, null, true);

But the prefab isnt kill himself. How can i set a alive time or kill the prefab?

 

I tested to create a prefab but i cant create an prefab. How to create a prefab?

Code:

            var ent = GameManager.server.CreatePrefab("assets/bundled/prefabs/fx/smoke/generator_smoke.prefab", airplane.transform.position, new Quaternion());
            ent.Spawn(); //<- Doesn't work
            timer.Once(time, () =>
            {
                ent.Kill(); //<- Doesn't work
                SpawnEntity(time);
            });