To stop your program you have to use kill your_pid command code example

Example 1: kill app at port

#To list any process listening to the port 8080:
lsof -i:8080

#To kill any process listening to the port 8080:
kill $(lsof -t -i:8080)

#or more violently:
kill -9 $(lsof -t -i:8080)

Example 2: kill linux port

sudo fuser -k 1883/tcp