If you have added child products, maybe with the same name and just different sizes/options as the parent, and want to remove the child name from the drop down..
go here:
In administrator\components\com_virtuemart\classes\ps_product_attribute.php comment out following code at/or about line 301:
$html .= $db->f( "product_name" ) ." - " ;
So the above should now look like this:
// $html .= $db->f( "product_name" ) ." - " ;
You can see the difference in the images attached - named before and after.
[attachment cleanup by admin]