PROBLEM:

Unable to rename [DatabaseName]. (ObjectExplorer)

Rename failed for Database[DatabaseName].  (Microsoft.SqlServer.Smo)

The database could not be exclusively locked to perform the operation. (Microsoft SQL Server, Error: 5030)

SOLUTION:

ALTER DATABASE <DBNAME>  SET SINGLE_USER WITH ROLLBACK IMMEDIATE
GO
SP_RENAMEDB <oldname>,<Newname>
Go
ALTER DATABASE <NEWDBNAME>  SET MULTI_USER — set back to multi user
GO