how to kill pid in ubuntu code example

Example 1: ubuntu kill process

pidof slack 
9734 9718 9716 9708 9622 9619
sudo kill -9 process_id

pidof apt 
9734 9718 9716 9708 9622 9619
sudo kill -9 9734 9718 9716 9708 9622 9619

Example 2: kill process ubuntu

sudo kill -9 process_id

Example 3: kill pid

Find PID of process to kill with:
ps ax
Then just specify "kill PID" command as for example:
kill 16320
kill -9 16320 	#Force kill in case process is not answering.

Example 4: kill pid

lsof -i:3000           // Change 3000 to whatever your port is!
sudo kill 9 <PID>      // Change <PID> to the Pid number the above command returns