According to the simple meaning of the text, it seems God took Pharaoh's free will. Rabbi Fohrman argues that the precise language-- kaved/chazek--shows that God DID allow Pharaoh to pursue his vision
Moshe complained to God that even though he would have the best human understanding of the Divine will, he had difficulty bringing it down to regular people. That role-"turgaman/navi"-Aharon filled