How do I use a delay?

I have a working gun, where it shoots every 0.5 seconds. But, all the clones of my projectile are really lagging my scene. So… I wish to kill a fired projectile after an amount of time. How do I do this? My code so far is attached

#pragma strict
var projectile : Transform;
var myVar : boolean = false;
public var spawn : GameObject;


function Start () {
	InvokeRepeating("Shoot", 0, 0.2);
}


function Update () {
	
	if(Input.GetKey(KeyCode.Space)){
		myVar = true;
	}else{
		myVar = false;
	}
}

function Shoot(){
	if(myVar){
		 var pel = Instantiate(projectile, spawn.transform.position, spawn.transform.rotation);
		pel.rigidbody.AddForce(transform.forward * 5000);
	}
}

Do Destroy(gameObject,2); In the update, you could try putting it in the start, idk if it’ll work the same. Haven’t tried.

I think this is how you do it. You would do that for C# with the exception that there’d be an F after the 2 for Float.