Do you agree with Okonkwo when he gives the fatal blow to Ikemefuna with his machete?

No. Okonkwo has no obligation to take part in the killing of Ikemefuna; in fact, he is discouraged from taking part in it at all by Ezeudu, the oldest man of the village. Ikemefuna calls Okonkwo his father, so it is understandable that he will not want to take part in the murder. Okonkwo disregards this option, and when Ikemefuna turns to him for help, Okonkwo gives him a fatal blow from his machete. Once again, Okonkwo fears being seen as weak rather than following his feelings.