The kill command kills a process by name. It should only be used in extreme circumstances as the DLLs attached to the process are not informed about the termination of the process and also the child processes (if any) are not terminated.
Syntax: kill <p_name>
Here, the "p_name" is the name of the process. For example, if you want to terminate notepad's process you can give the following command:
kill notepad.exe
Note that the kill command only terminates a single process. If there are more than one processes having the same name that you would like to terminate then you should use the command multiple times.