how to kill a process in ubuntu terminal 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 a process on Ubuntu

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