Changing the TPM owner password
Applies To: Windows Server 2008
As with any password, you should change your TPM owner password if it has become compromised (that is, if you suspect it is no longer a secret).
If you want to invalidate all of the existing keys created since you took ownership of the TPM, you can clear the TPM instead of changing your owner password.
Important
Clearing the TPM could result in the loss of data. To avoid data loss, make sure you have a backup or recovery method for any data protected or encrypted by the TPM.
If you want to keep all existing keys and data intact, but wish to disable the services provided by the TPM, you can turn off the TPM instead of changing your owner password.
Additional references