Tomcat, being a webserver program, should run independently of anyone's terminal window.
So, why would you like to kill it?
Many programs run without a TTY (a terminal window) associated to them. That's normal
for services like ftp, http (web), etc.
Furthermore, if your "ps" lists tomcat, then it is already running.
But how do you run it exactly? Using a script in /etc/init.d? As a daemon?