Run command-line as an Administrator. Then run the below mention command. type your port number in yourPortNumber
netstat -ano | findstr :<yourPortNumber>
Red coloured circled area shows the PID (process identifier)
Then you execute this command after identify the PID.
taskkill /PID <typeyourPIDhere> /F
P.S. Run the first command again to check if process is still available or not. You'll get empty line if process is successfully ended.