Titus was not circumcised. He went with Paul to Jerusalem as an uncircumcised Gentile convert and he returned from the city the same. The fact that he was not compelled to be circumcised establishes a principle that is applicable to all Gentile converts, specifically: circumcision is optional; it is not required.1
3 But even Titus, who was with me, was not forced to be circumcised, though he was a Greek.