What does it mean when you have a dream about kill yourself?

It Does Not mean a real physical death, the death is a change of the ways and even ideals of what you are and think now. It may be telling you that a change is needed in lifestyle, a change of friends or job or location. It may be one needs to move on to take a new and better path.

It means that there is some aspect of yourself that you don't like and want to change. Dreams typically exaggerate everything, so that an ordinary problem is visualized as a huge crisis. Because this question is posted on the day before Easter, on the morning after Good Friday (commemorating the sacrificial death of Jesus Christ) this dream could have a religious link, referring to the need to "die to sin" or "put to death this body of sin" in order to live in the righteousness of Christ. Such expressions speak of spiritual realities, not physical suicide.