Redirecting the output of ps command,getting process id and killing that process using shell script

I want to write a shell script to find the running process for a given user and kill the process by getting the respective process ID. Its like ``` ps -ef | grep dinesh ``` After this, i am getting the output as the following ``` dinesh 19985 19890 0 11:35 pts/552 00:00:00 grep dinesh ``` Here 19985 is the process ID. I want to kill that process. How can i achieve this using script? I have to parse the ps command output and get the process ID Thanks in advance.