sudo kill -9 $(sudo lsof -t -i:9001)


lsof   - list of files(Also used for to list related processes)

-t     - show only process ID

-i     - show only internet connections related process

:9001  - show only processes in this port number

kill   - command to kill the process

-9     - forcefully

sudo   - command to ask admin privilege(user id and password).