Reclaiming unallocated space from tempdb database in SQL Server Express 2012
I have done it using


  DBCC SHRINKFILE ('tempdev',10)


Somehow DBCC SHRINKDATABASE was not working. Even DBCC SHRINKFILE ('tempdev',0) or DBCC SHRINKFILE ('tempdev') doesn't work. We have to assign some figure in MB to which it will shrink the database to.