[Calash]

You can go to the front page of your UserCP and disable it from posting to your wall for your account.

Unlinking an account depends on how you linked it to begin with. If the account was there before you can just delete the entry in the nonvbuser table and login normally with your old password. If the account was made by the bridge you will need to input a valid email and change your password with the lost password recovery forum. Once you have a valid password you can remove the entry in the database and you will be all set.