So you have two ways to do that:
First : The easiest: Navigate to the source document library and open the "explorer view" then copy the documents and move those to the new path
Second: Type a script or program
$src = $web.Lists [ "source" ]
$dest = $web.Lists [ "dest" ]
$destFiles = $dest.Folders [ "mydoc" ]
foreach ( $item in $srcLibrary.Items )
{
if ( $item.File )
{
$file = $item.file.OpenBinary()
$destURL = $destFiles.Folder.Url + "/" + $item.file.Name
$destFiles.Add ( $destURL, $file, $true )
}
}
BTW You will lost all your versions if the version option was enabled