Mary Warren, the servant of John and Elizabeth Proctor in Arthur Miller's "The Crucible," does not want to kill Abagail Williams. In fact, Mary Warren is deathly afraid of Abagail Williams. Abagail, or Abby, is the "leader" of the band of girls leading all of the accusations against the numerous people in Salem. Mary believes that she will come under the wrath of Abagail if she (Mary) speaks out against her (Abagail).
Therefore, Mary Warren does not necessarily want to kill Abagail Williams; though she would, most likely, not care if Abagail were to disappear, as she does late into the play. Mary Warren may be angry with Abagail for setting her up (by setting her up regarding Elizabeth being named a witch for the poppet), nothing is ever said about wanting Abby dead.