Here is an example that will decompress a file that was compressed using the Microsoft compress.exe utility utilizing the -r (rename) command line switch. Note: If you already know the expanded name of the file, or it was not compressed with the -r command line switch, then simply omit the code associated with the GetExpandedName function, and directly hard code the file name as needed.

uses LzExpand;

{$IFNDEF WIN32}
const MAX_PATH =  44;
{$ENDIF}
procedure TForm .Button Click(Sender: TObject);
var lpDstFileName : PChar;
  SrcFile : integer;
  DstFile : integer;
  SrcOs : TOFSTRUCT;
  DstOs : TOFSTRUCT;
begin
   GetMem(lpDstFileName, MAX_PATH);
   GetExpandedName('C:\TestFile.bi_', lpDstFileName);
   SrcFile := LZOpenFile('C:\TestFile.bi_', SrcOs, OF_READ);
   DstFile := LZOpenFile(lpDstFileName, DstOs, OF_CREATE);
   LZCopy(SrcFile, DstFile);
   LZClose(SrcFile);
   LZClose(DstFile);
  FreeMem(lpDstFileName, MAX_PATH);
end;