There are 2 options available:
Option 1
You send GMS the Service ID deactivation request. Such a request should be sent before the billing date. This way, you avoid the MMC payment for the given ID.
Example: You would like to have an ID deactivated starting July. Therefore, the request should be sent no later than June 29. If the request is sent on July 1 or later, the ID will be deactivated only next month – in August. In such a case, the MMC fee for July will be applied.
Option 2
You leave the ID active and do not send the request at all. In this case, you will pay the MMC for this ID.
Please note: Viber allows for up to 3 ID deactivations per year. After 4th deactivation the ID automatically becomes inactive and can`t be activated till the end of the current year.