I have a ganglion cyst in my right wrist . doctor said its harmless and not to worry . but its kind of round swelling . how will it go back ?

Depends: It may disappear on it's own, it is also possible it will not. If you want it to be "removed" it is, most often, a simple procedure. A needle aspiration is performed to remove the synovial fluid and a steriod will be injected. The area may also be splinted for a couple weeks. This should resolve the issue. Again, it is not a threatening situation and it will not spread to other areas.

Ganglion observe: You have a ganglion cyst which can be observed. Your doctor said not to worry as a way to reassure you. Treatment is available but it can recur. Many patients observe their ganglion cysts for life. If it bothers you enough then tell your doctor of your concerns and asks for a referral to a surgeon or orthopedist. Be well and stay healthy.

Yes , by surgery: Only way is by surgical removal , a simple out patient procedure , aspiration will not cure.