The admin guide only gives the following for resets:
Restore Factory Defaults
The Restore Defaults Web page lets you restore the factory default settings on the IP Conference Station.
Opening the Restore Defaults Web Page
Click Restore Defaults in the navigation pane.
Restoring Defaults
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Caution When you restore the factory defaults, all current settings, configuration, and data, including the phone book entries, are lost.
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To restore defaults:
Click Restore Defaults.
I would assume that you need to be logged in as the admin to reset the password so might not be of much help in this instance.
However this might help:
CSCin62150
When the Cisco CallManager release is changed, and the IP Conference Station is downgraded from the P00503010400 release to the P00503010300, P00503010200, or P00503010100 release, the administrator password is lost.
Workaround: On the IP Conference Station, press **1 to restore the factory default settings.
Regards
D