Currently the only way to delete an actor is through the actor control panel. I'm aiming to change that in 1.5. Do you know about tiled actors? You can create tile sheets and use that instead of cloning. In the tile editor, you can easily delete and create actors.
Once i have a good amount of grass tiles using the array function, i cant scroll in the area without moving tiles.
If you hold right control, and use left click, you can drag the stage as if there wasn't an actor there.