can be made lesser only and only by Speech therapy
. So you should take the help of a speech therapist
. Also, I'd suggest you to visit a Psychologist
as confidence plays a great role in dealing with this problem.
I'd suggest you to speak very slowly, word by word. People may make fun of this but believe me, slowly you'll get better at it.
Hope your query is answered. Feel free to ask if you have any doubts.
Wishing you good health.