For version 9:
www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/cucos/9_1_1/CUCM_BK_C5D96C80_00_cucm-os-admin-guide-91/CUCM_BK_C5D96C80_00_cucm-os-admin-guide-91_chapter_010.pdf
For version 5 to 8 read the following info taked from this post:
https://supportforums.cisco.com/document/65041/how-reset-passwords-cucm
If you do not remember the Administrator and/or Security passwords, you can follow the bellow steps in order to reset the Administrator password. This procedure can be done with CUCM 5, CUCM 6, CUCM 7 and CUCM 8:
Step 1 Log in to the system with the following username and password:
•Username: pwrecovery
•Password: pwreset
The Welcome to admin password reset window displays.
Step 2 Press any key to continue.
Step 3 If you have a CD or DVD in the disk drive, remove it now.
Step 4 Press any key to continue.
The system tests to ensure that you have removed the CD or DVD from the disk drive.
Step 5 Insert a valid CD or DVD into the disk drive.
The system tests to ensure that you have inserted the disk.
Step 6 After the system verifies that you have inserted the disk, you get prompted to enter a new Administrator password.
Note The system resets the Administrator username to admin. If you want to set up a different Administrator username and password, use the CLI command set password
Step 7 Reenter the new password.
The system checks the new password for strength. If the password does not contain enough different characters, you get prompted to enter a new password.
Step 8 After the system verifies the strength of the new password, the password gets reset, and you get prompted to press any key to exit the password reset utility.
Note To perform the password reset process, you must be connected to the system through the system console, that is, you must have a keyboard and monitor connected to the server. You cannot reset a password when connected to the system through a secure shell session.
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