SQL holds a lot of cached information in tempdb. Until it’s cleared it won’t allow tempdb to be shrunk. So here’s a quick script you might have some joy with (obviously be aware that you will suffer the cost of losing this cached information) (thanks to MSDN);
USE [tempdb]
GO
DBCC DROPCLEANBUFFERS
GO
DBCC FREEPROCCACHE
GO
DBCC FREESESSIONCACHE
GO
DBCC FREESYSTEMCACHE ( ‘ALL’)
GO
DBCC SHRINKDATABASE (tempdb,10)
GO
IT Bytes 