How to remove SharePoint_Config database?

I tried to remove everything from my test farm to create a clear environment for restoring all the content from production farm.

Unfortunattely, I didn't read any guides about this and simply tried to delete all web applications, pools, databases manually. I successfully dropped all databases from SQL Server except Sharepoint_Config. The error "Cannot drop database "SharePoint_Config" because it is currently in use." appears.. I disabled all services that have "Sharepoint" in their name, but that gave no result..

Which processes could be related to the Sharepoint_Config db?

Or may be there is another way to force deleting this db?

Thanks in advance,

Anton