You can change the OS admin password (e.g. Administrator) using the Microsoft user manager (just as you would for any other account).  If you need to modify existing service accounts or the cluster password using the Admin Utility.  From the following URL:

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_configuration_example09186a008073f593.shtml#maintask1

Change Passwords in Cisco CallManager

You can change the administrative passwords using either one of  these       methods on Cisco CallManager servers that run on a Windows Operating  System. It       is necessary to reboot the cluster after you change the passwords in  order to       remove any potential problems with Windows password caching.

Note: If the Lightweight Directory Access Protocol (LDAP) setting  is           Microsoft Active Directory instead of DC Directory, you must manually  set this           password using Active Directory.

Note: The Administrator account serves as the default Windows NT           administration account. Cisco CallManager does not use this password.

• Choose Start > Program Files > Administrative Tools > Computer           Management > Users, select Administrator           Account and right-click Set           Password.

• The Windows Administrator account password is a login password into           the physical server. You can change the Windows Administrator password  when you           press Ctrl+Alt+Delete and click on Change           Password.

CCMPWDChanger Tool

The CCMPWDChanger tool is used to change the passwords for  Directory       Manager, CCMSysUser, CCMAdministrator, and IPMASysUser.

From the Cisco CallManager, choose Start >       Run, type CCMPWDChanger and press       Enter. Refer to       Change        the Password for more details on the CCMPWDChanger tool.

Note: The CCMPWDChanger tool should be used only on the Cisco  CallManager           Publisher server.

Change CallManager Services Passwords with the Admin  Utility

The Admin Utility is used in order to change the services password  and       synchronize for SQLSvc, CCMServiceRW, CCMService, CCMCDR, and CCMUser  in the       Cisco CallManager cluster. Run this from C:\Program       Files\Cisco\Bin\Adminutility.exe. The Admin Utility changes the       cluster private password, which in turn generates new encrypted  passwords for       the SQLSvc, CCMServiceRW, CCMService, CCMCDR, and CCMUser accounts.  Keep this       in mind when running this utility. Refer to       Check        Password Synchronization with the Admin Utility in the Cisco  CallManager       Cluster for more information on the Admin Utility.

HTH.

Regards,
Bill

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