It's kind of like hopping off a diving board. There's no real way to get over it but to force yourself, give yourself the push and take a leap. It's just all about forcing yourself. Another thing with practicing jumping from a high diving board is practicing hopping from lower heights first. Same thing with singing in front of crowds. Try singing in front of family, then friends. Then practice being outgoing in public places. From there it should be easier to take the leap! :):):) I really hope this helps <3
To get rid of shyness, the most important thing is to believe in yourself that you can do it. Ways to get rid of shyness include; going out and mingling with people, smile and try to at least look relaxed in the company of others. You can also join personality development classes.