Firstly, I think you therefore mean the scene bounds. Screen bounds are the area you can see, and as you said you want it to die when it goes outside the "map" or the scene. You can find blocks for scene width and height under Scene>World in design mode, or just search for them. You then do a check to see if the actor's x is less than 0 or more than the scene's width, or if its y is less than 0 or more than the scene's height, and if so then recycle it.