It is right in the documentation... But remember it is just a (mostly) CentOS compatible Linux system...
To reset the Administrator password for the "admin" and "root" users:
1. Open a terminal session to the server or access the console.
2. Physically shut down the server and start it up again.
3. When the GRUB boot loader splash screen appears, press the "a" key.
- The load process stops, enabling you to append arguments to the kernal boot line.
4. In the kernel boot line, type " single" (note the leading space) and then press Enter.
5. When the bash shell prompt appears, do the following:
• Type "passwd root", enter a new password, and then press Enter.
• Type "passwd admin", enter a new password, and then press Enter.
6. Type "exit" and press Enter to resume the boot sequence.
Note: Although you can enter unique "root" and "admin" passwords, typically you
would enter the same value for both users.
