Admin password for provisioned Grandstream GRP2602

I set up and provisioned two Grandstream GRP2602W desk phones on the same LAN.  I now need to move one of the phones to a different network, which requires the admin password.  I am the owner of the Zoom account and my Zoom password is not accepted.  Neither is the default password on either of the two desk phones.  Grandstream support tells me that, if the phone has been provisioned, I (the admin) should know the admin password.  Any ideas on where I can determine what "other" admin password was set during the original provisioning?  Thanks.