I'm a by born Muslim and I did many sins and don't want to do anymore. Can I commit suicide in order to stop myself from doing sin?

All Prophets and Aimmah came to this world to be examined and show the right path to all Humanity. That is why as long as we are alive and live in this world we can change our destiny and seek Allah (swt) pleasure. But after death this blessing (life in this world) of Allah will be stopped. If you want to stop your life, it means you are giving away the opportunity which Allah (swt) has given to you. Suicide is a great Sin and after that there will not remain any chance to seek Allah’s pleasure. Also a person will not receive Prophets and Aimmah (a.s)’s intercession.
No one can say that his/her deeds will be accepted on the day of Judgement. We all live in this world with hope and fear that is the very sign of a believer. Therefore please believe in Allah’s mercy and ask forgiveness for your mistakes and live your life free of mind.