Welcome to our community forums and we appreciate your post. There is not a way to disable an email account without removing it. You could create an auto-reply until you want to make the email account active again.
Godaddy will never be a serious email option for a real business that requires security without a disable option. You may think you are because you have big clients but that also may be one of the reasons there are so many breaches in the world. There is no quick way to disable a disgruntled employees account. This service is an expensive waste other than to destroy my blood pressure