Hypnosis may be an option.
In other instances seeing a therapist might help.
More often than not there was "trigger" or event which occurred that caused one to develop social anxiety. Sometimes as children we come up with various "defense methods" to protect ourselves from hurt and never shed them even after becoming adults.
It's hard to get ahead in life with social anxiety. I know people in my family who have no friends outside of the family and seldom leave home unless it's for work or to run errands. No social events!