Using a scalpel, cut into the urethra, using the sound as a backing. Suture the edges of the hole. Circumcision is the removal of the foreskin. There are some medical conditions that make circumcision desireable. Other people desire circumcision for primarily aesthetic reasons, either for the uncovered glans, or the look and feel of tight skin over the shaft of the penis.
Doctors are the obvious choice.
There are also a variety of private non-medical practitioners. There are some tools such as Taraclamps which can in theory be used at home. Outside of infection and bleeding, there is some risk of loss of sensation due to the thickening of the skin of the glans. Some people lose some degree of ejactulatory control due to loss of fine nerves. However, almost everyone is pleased with the overall result.