When you delete an account, the account is removed from the server, the content of the account, including messages, address books, and calendar information and files in the Briefcase folder are deleted. The number of accounts used against your license is automatically changed,
You can change the status of an account to Closed if you are not sure that you want to delete the account and contents. When a mailbox status is Closed, the login is disabled and messages are bounced. A closed account does no change the account license.