To deter someone from doing something means to make them not want to do it or continue doing it.
例句
Supporters of the death penalty argue that it would deter criminals from carrying guns...死刑的支持者認為它能阻嚇罪犯攜帶槍支。Arrests and jail sentences have done nothing to deter the protesters...逮捕和監禁都沒能嚇倒抗議者。