How to shrink the TempDB database without stopping MS SQL

Here's how:

DBCC FREEPROCCACHE

GO

DBCC DROPCLEANBUFFERS

GO

DBCC FREESYSTEMCACHE ('ALL')

GO

DBCC FREESESSIONCACHE

GO

DBCC SHRINKFILE (TEMPDEV,1024)

GO

Taken from : http://calyansql.blogspot.ca/2012/04/shrink-tempdb-data-file-without-sql.html