• Or Kill node process running under certain port.

Goto the command line and find the "PID" of the process:

$ lsof -i tcp:8000 //where the port you want to kill is 8000

The above command opens a list of all processes with their "PIDs".

...
COMMAND  PID    USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
node    7069 chidera   20u  IPv6 891480      0t0  TCP *:8000 (LISTEN)
node    7069 chidera   22u  IPv6 892242      0t0  TCP localhost:8000->localhost:39292 (ESTABLISHED)
...

From the output, the unique PID of my process on PORT 8000 is "7069",

node    7069 chidera   20u  IPv6 891480      0t0  TCP *:8000 (LISTEN)
node    7069 chidera   22u  IPv6 892242      0t0  TCP

Finally, Kill the process using it's "PID" like so

$ kill -9 7069

Alternatively, you could kill all node processes using

$ pkill node

And that's all.