What if Redhat/CentOS forgets the root password?

What if Redhat/CentOS forgets the root password?
1. I forgot to install the redhat linux root Password on my vmvm. I just wanted to reinstall it. But I thought there was another single mode in linux. Using single, I could directly go to the character interface and modify it; 2. Start the vmvm and start the linux system. 3. Enter the linux Startup interface and press e to enter the following interface. 4. Press select kernel/vmlinuz-2.4.20-8 ro root = LABEL =, press the e key, and then enter "single" in "space". 5. Press enter after the input is complete. 6. Press the B key to boot and enter the character interface; 7. Enter passwd root to modify the root user password. 8. Enter the new password twice and press Enter. The modification is successful. 9. Enter reboot to restart; 10. After restart, use the new password to log on;