Document.TextLineEnding (Word)

Returns or sets a WdLineEndingType constant indicating how Microsoft Word marks the line and paragraph breaks in documents saved as text files. Possible return values are wdCRLF - Carriage return plus line feed, wdCROnly - Carriage return only, wdLFCR - Line feed plus carriage return, wdLFOnly - Line feed only, wdLSPS - Not supported.

Sub LineEndings() 
 ActiveDocument.TextLineEnding = wdCROnly 
End Sub