What happens when you delete a user from the Office 365 control panel? Automatically they are moved into a recycle bin for 30 days, so if you needed, this objects can be recovered easily if the deletion was not intended.
However, if you want to permanently remove a deleted user in Office 365 you can use PowerShell.
First, connect to your Azure Active Directory by running Connect-MsolService and entering your admin credentials in the dialog box that appears.
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