Error while unprovisioning of Sync DB $syncDB.Unprovision()

My User profile synchronization service is stop. it wad hang in startup and then i stop / unprovision using $syncDB.Unprovision()

when i run following command

$upa.ResetSynchronizationDatabase()
i am getting following error
Exception calling "ResetSynchronizationDatabase" with "0" argument(s): "Cannot
open database "Sync DB" requested by the login. The login failed.
Login failed for user 'domain\farmaccount'."
At line:1 char:34
+ $upa.ResetSynchronizationDatabase <<<< ()
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : DotNetMethodException

Resolution :

If sync database status is set to single, then change it to multi user. Also make sure, farm account have dbowner access on it.

If issue exist, try to execute same commands using new powershell window session.