At which city did John Mark leave Paul and Barnabas to return to Jerusalem?

Answer: Perga in Pamphylia

After sailing from Paphos, they came to Perga in Pamphylia, where John left them to return to Jerusalem.

“After setting sail from Paphos, Paul and his companions came to Perga in Pamphylia, where John left them to return to Jerusalem.”— Acts 13:13 (BSB)