Can God do wrong?
No. God is sovereign and absolute in power, yet He is righteous and can do no sin and no wrong. His thoughts and ways are higher than ours, so we are in no position to argue with or question what He does or why He does it.
The teaching explains that the potter-and-clay passage is tough, but the first point is that God is sovereign and absolute in power, so no one is in a position to argue with what He does or why. The Old Testament declares His thoughts and ways are higher than ours, not for us to question. Yet God is righteous; He can do no sin and no wrong. He also gives every human being free will. Pharaoh, when confronted with letting the Jews go, could have let them go, but his economic fear of losing slave labor kept him from doing so, and it did ruin the nation when they left.