how to change name of server host for ubuntu server 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: ubuntu chang host name

Type the following commands:
$ sudo hostname new-server-name-here