If they are purposefully wrecking things I would tell them no and they are not allowed to do that and why, firmly but calmly, and then remove the toy or whatever else and put it away. If they end up with no toys then too bad, they will learn. I do this with DD already. She can't play with things if she is going to break them. She understands already and knows to me gentle.

That's just what I'd do. HTH.