How to get rid of sebaceous cyst at the back but not infected.

Multiple Options: You can go to a doctor and see the multiple options that are available. You can have it injected, an excision and drainage may also be available, a total excision, minimal excision, or laser. If it is bothering you, please go see a doctor and they can offer you some of these choices and see what works best for you :].

A minor surgery: These are usually treated with a minor surgery, where the cyst, and it's entire lining, is removed. This is typically done under local anesthesia.