A dream where there is a killing symbolizes violence. It can suggest that you are facing emotional difficulty such as feelings of anger or rage.
If you kill someone or something then it implies that someone may be having an influence on you, you are seeking the answer to a problem, or you are feeling a build up of anger or a sense of losing your self-control in some aspect of your life. Alternatively, it may suggest that you are trying to get rid of a part of yourself or an aspect of your life that the person or thing being killed represents. This may be old habits or ways for example.