CopyAllChildren() doesn't exist as far as I know.
ClearAllChildren() does exist however. Here's an example for using it.
1 | game.Workspace:ClearAllChildren() |
3 | game.Lighting:ClearAllChildren() |
5 | game.Teams:ClearAllChildren() |
To clone something, its fairly simple. Here's an example.
1 | game.Workspace.Part:Clone() |
However, you can also simply destroy one specific thing rather than destroying it all. There is two methods.
1 | game.Workspace.Part:Destroy() |
3 | game.Workspace.Part:Remove() |
I don't really see a difference between Destroy() and Remove(), but hey, it's your choice on what to use. I hope I was helpful. :)