Enable Root Login in Ubuntu 18.04

Step 1: Login into your account and open terminal

Step 2: Type the following command to setup password for root account

sudo passwd root

Step 3: Open file /etc/pam.d/gdm-password

sudo nano /etc/pam.d/gdm-password

Step 4: Comment out the following line by placing # infront of it

#auth    required    pam_succeed_if.so user != root quiet_success

Step 5: Reboot the system