Mailbox duplicated after migration error

Good afternoon, I am writing to you for a problem on an Exchange 2019 Standard. 
I launched the migration of a mailbox from Database2 to Database1 and, unfortunately, 
suddenly both databases were dismounted with relative failed migration. 
Now I find myself with 2 mailboxes with the same GUID in two different databases and both active, 
with the email being stored in the source database (Database2). 
How can I delete the unused mailbox from the migration target database (Database1)?
Thanks, AUberti