ubuntu change hostname cant access ssh code example

Example 1: how to change hostname in ubuntu

#1- Delete the old name and setup new name
sudo hostnamectl set-hostname newHostname

#2- Edit the /etc/hosts file:
sudo nano /etc/hosts

#3- Reboot the system 
sudo reboot

#4- To check the new hostname
hostnamectl

Example 2: change hostname ubuntu 20.04

#Change hostname
sudo hostnamectl set-hostname newHostName 
#Edit the /etc/hosts file, and replace existing hostname with a new hostname.
sudo nano /etc/hosts
#Reboot the system to changes take effect
sudo reboot