Reclaiming data file free space after deleting a large amount of data
First, are you sure the data growth won't happen again? If there's a realistic chance it will and the empty space doesn't hurt you, leave it, do NOT shrink the database.

However, if you're positive you want to reduce the data file size, then you should be aware of the pitfalls of data file shrinking:


It causes massive index fragmentation.
Affects performance WHILE it's running and AFTER it's run (one exception - the WITH TRUNCATEONLY option, if you're just removing free space at the end of the file)


I refer to the advice of Paul Randal from his article "Why you should not shrink your data files" (read the whole article to get a clear picture what happens with index fragmentation):


  The method I like to recommend is as follows:
  
  
  Create a new filegroup
  Move all affected tables and indexes into the
  new filegroup using the CREATE INDEX … WITH (DROP_EXISTING = ON) ON
  syntax, to move the tables and remove fragmentation from them at the
  same time
  Drop the old filegroup that you were going to shrink anyway
  (or shrink it way down if its the primary filegroup)
  
  
  Basically you
  need to provision some more space before you can shrink the old files,
  but it’s a much cleaner mechanism.
  
  If you absolutely have no choice and have to run a data file shrink
  operation, be aware that you’re going to cause index fragmentation and
  you should take steps to remove it afterwards if it’s going to cause
  performance problems. The only way to remove index fragmentation
  without causing data file growth again is to use DBCC INDEXDEFRAG or
  ALTER INDEX … REORGANIZE. These commands only require a single 8KB
  page of extra space, instead of needing to build a whole new index in
  the case of an index rebuild operation.
  
  Bottom line – try to avoid running data file shrink at all costs!