Remove a running process from memory.

Syntax
      KILL [option] process_id
      KILL [option] task_name
      KILL [option] window_title

Option
        -f     Force process kill

Note: Kill -f basically just nukes the process from existence, potentially leaking a lot of memory and losing any data that the process hadn't committed to disk yet. It is there for worst case scenarios - when you absolutely must end the process now, and don't care whether proper cleanup gets done or not.

In WindowsXP, KILL is replaced with the superior TASKKILL - Allowing you to specify a remote computer, different user account etc - for more details run TASKKILL /?