How do I unlock a content control using the OpenXML SDK in a Word 2010 document?

The openxml SDK provides the Lock class and the LockingValues enumeration for programmatically setting the options:

• Content control cannot be deleted and
• Contents cannot be edited

So, to set those two options to "false" (LockingValues.Unlocked), search for all SdtElement elements in the document and set the Val property to LockingValues.Unlocked.

The code below shows an example:

static void UnlockAllSdtContentElements()
{
  using (WordprocessingDocument wordDoc =
    WordprocessingDocument.Open(@"c:\temp\myword.docx", true))
  {        
    IEnumerable<SdtElement> elements = 
      wordDoc.MainDocumentPart.Document.Descendants<SdtElement>();

    foreach (SdtElement elem in elements)
    {
      if (elem.SdtProperties != null)
      {
        Lock l = elem.SdtProperties.ChildElements.First<Lock>();

        if (l == null)
        {              
          continue;
        }

        if (l.Val == LockingValues.SdtContentLocked)
        {
          Console.Out.WriteLine("Unlock content element...");
          l.Val = LockingValues.Unlocked;
        }
      }
    }
  }
}

static void Main(string[] args)
{
  UnlockAllSdtContentElements();
}