Is it possible to carry out surgical operation on a patient who is not sick?

Yes

Circumcision for example

Removing of the appendix can be justified if working in a remote area with minimal medical facilities for emergencies.

I believe that workers in the Artic/Antartic have their appendix removed prior to posting.

It has to be medically ethical -and not purely for cosmetic reasons.

Remember however that plastic surgery is usually performed on the healthy-that is not sick

Sure, every cosmetic surgery is performed on a healthy patient. You can have a preventive mastectomy, etc.

surgical operations could also be done on people who donate bone marrow, or kidney, or part of their liver, etc to someone who's sick to save his (the sick person's) life. :)

Yip but it would be kinda random!