Change your username -UBUNTU

If you want to change your username

Restart in recovery mode and go to the root prompt shell

 ("Drop to root shell prompt")

1. First remount the root
1. mount -o remount,rw /
2.  change the username and home folder name

1. usermod -l <newname> -d /home/<newname> -m <oldname>
   

3. reboot
4. Resume normal boot