Boot to the GRUB menu and enter the edit mode. Use your arrows to navigate to the the menu item you would normally boot your RHEL 8 Linux system from. Press e to start editing the selected menu item.
Perform a break at an early stage of the boot process by typing rd.break at the end of the line starting with Linux. Add systemd.debug-shell after rd.break
Once ready press CTRL+X to start the RHEL 8 boot process
To access the debug shell on TTY9. Press CTRL+ALT+F9 (Do not hit any other button!)
On TTY9:
mount -o remount,rw /
passwd root
touch ./autorelabel
exit
Press CTRL+ALT+F1
Press ENTER
Login with root and the new password.
