1. Launch the KVM interface for your server to access it from the console.
2. Interrupt GRUB by typing a character such as "space" 
3. Append to the kernel line by typing "a", backspacing through "rhgb quiet" and appending "1" and pressing <enter>. 
4. This will give you a root shell and not a login prompt. From there you can use the "passwd" command to set a new root password.
5. Restart the server and allow it to boot normally.

Single user mode can be used to reset other user passwords as well as perform other administrative tasks.