Change Ubuntu root password without getting “Give root password for maintenance”

Reboot machine;
Press ‘Esc’ to get to the GRUB menu;
Select the image;
Press ‘e’ to edit;
Change the kernel line from ‘ro’ to ‘rw init=/bin/bash’

From:

To:

Press ‘ctrl+x’ to boot;

From the bash shell:

passwd <username>