Remove SKU label from product reference select list
In a custom module (or theme) you could implement hook_field_widget_WIDGET_TYPE_form_alter() and alter the labels of the options (i.e., stored in the $element['#options'] variable). If I'm not mistaken your function would be mymodule_field_widget_options_select_form_alter(&amp;$element, &amp;$form_state, $context), where mymodule is your custom module (theme) name. Don't forget to check for which field you're altering the options, you can find this in $context['field']['field_name'].

If you don't want to write custom code, you could as an alternative use the Entity reference module in combination with Views. Hereby you can use the output generated by a view as an option list for the (entity) reference field (pointing to your product).