Recovery password on Redhat7 or CentOS7

1. Start or reboot a system to get into the boot menu.

2. Press any key to stop the auto selection of a menu item.

3. Ensure the kernel you intend to boot into is highlighted and press the "e" key to edit the entry.

4. Navigate to the linux16 kernel line and hit the "end' key to go to the end of the linux16 line.

5. Append rd.break to the linux16 kernel line.

6. Hit crtl + x to continue.

7. The system will boot into an emergency mode that has the /sysroot directory mounted as read only.

8. Mount the /sysroot directory with read and write permissions.

mount -oremount, rw /sysroot

9. Switch into chroot jail and set the /sysroot as the root file system.

chroot /sysroot

10. Reset the root password.

passwd root

11. Clean up, -> Make sure that all unlabled files get relabeled during the boot process (for SELinux).

touch /.autorelabel 

12. Exit chroot jail.

exit

13. Exit the initramfs debug shell.

exit

Troubleshooting notes:

Go though the process and reboot but password not changed?

1. Chances are the touch ./autorelabel was missed or performed incorrectly.
2. Chances are the file system was not mounted as read/write so the changes made were not persistent.