How to remove unused versions of documents?

Question

I've disabled versioning on a document library that has grown to 4GB in size for only around 900 documents. Although the versioning is no longer enabled the previous versions of the documents still exist in the AllDocStreams table in the content database. How do I get SharePoint to automatically release the space used by the no longer used versions of the documents?

I'd read somewhere that the unused documents are removed when the user next updates the document and SharePoint determines the previous versions are no longer required. However, I'd prefer to release the space immediately if possible.

Answer 1

Here are two solutions using PowerShell:
PowerShell Script to Delete All Versions in a Document Library
SharePoint PowerShell: Delete old versions of documents and items.

Essentially this should work (from first link):

$web = Get-SPWeb http://localhost
foreach ($list in $web.Lists)
{
  # examine if BaseType of list is NOT a Document Library
  if ($list.BaseType -ne "DocumentLibrary") 
  {
    # forget the rest and return to top
    continue
  }
  # loop through each item
  foreach ($item in $list.Items)
  {
    # work with the file object as we're in a document library
    $file = $item.File
    # delete all versions
    $file.Versions.DeleteAll()
  }
}
$web.Dispose();

I tested the $file.Versions.DeleteAll() and it worked for me