In ESI, you can only remove an Exchange mailbox database when a single mailbox database copy exists. Before removing the active original mailbox database, you must first remove all database copies. Removing mailbox database copies provides instructions.
To remove a mailbox database:
In the left pane of the ESI window, select Applications > Exchange > Mailbox Server and the applicable mailbox forest.
Click Mailbox Servers, expand the list, and select one or more mailbox databases to delete.
Note: To select multiple databases, press and hold Ctrl and select each database from the list. Each database is highlighted as it is selected.
In the Actions pane, click Remove Mailbox Database.
The Remove Mailbox Database wizard appears.
Confirm that the correct databases are listed.
To delete the disk that was created for the database, select Delete the corresponding disk, and then click Next.
Warning: All data is deleted with the disk and cannot be recovered afterward. This includes other data unrelated to the database.
In the Review Input Parameters page, confirm the parameters, and then click Next.
In the Progress page, click Next.
Note: Click More Information for more progress details. If a problem occurs, an error message appears along with options to resume or roll back the process. After the error is resolved, click Resume to resume the process. Click Rollback to revert to the previously executed step.
In the Summary page, click Finish.