You have to stop the boot process and enter single mode. The may be a knowledge base article, but this is how:
You can reset your root/admin password like this:
   1. Boot your server and use the arrow keys to select the kernel you would like to boot into.
   2. Press A , to append parameters to your grub boot settings.
   3. Be carefull not to change anything, only add the following:
      Code:
       single
      (Mind you there is a space before single).
   4. Press enter. you will be presented with a prompt.
   5. At this prompt type the following commands (followed by a return). You will be asked to provide a new password. Reset both your root and you admin password and set them to the same value:
      Code:
      passwd root
      Code:
      passwd admin
      .
   6. Reboot your server and everything should be okay now.