Rent A Shock to the System (1990)

When advertising executive Graham Marshall (Michael Caine) is passed over in favour of a younger and more ruthless colleague, he realises that his days are numbered. After accidentally causing the death of a man on the subway, however, Graham finds out just how easy it is to kill, and begins to employ his new-found skill in the boardroom. With his career revived, Graham then decides to apply his deadly methods in other areas of his life...