Clear old SharePoint 2010 Database after remove service application

When you remove your service application, you can see on page “Management Databases Upgrade Status” (http://central_administration/_admin/DatabaseStatus.aspx) still your database, but physically is database deleted.

In the event log can be repeated critical message..

SQL Database 'db_name' on SQL Server instance 'sql_instance' not found. Additional error information from SQL 

Server is included below.

Cannot open database "db_name" requested by the login. The login failed.
Login failed for user 'login'.

You can remove database using PowerShell…

get-spdatabase | where {$_.name -eq 'db_name'} | foreach {$_.Delete()};