Mount the partition by launching the following command:
mount /dev/vda1 /mnt
(the disk to mount can vary)
Then, do a chroot on the mount made:
chroot /mnt
Change root password:
passwd
Type the new password (it will not show on screen as you are typing)
Changing password for root user.
New password:
Retype new password:
A confirmation message will appear:
passwd: all authentication tokens updated successfully.
