How to create Sales Return Without Delivery Note in ERPnext

Hi @GGR,

That for, please apply the client script for Sales Invoice.

frappe.ui.form.on('Sales Invoice', {
   is_return: function(frm) {
       if (frm.doc.is_return === 1) {
           frm.set_value('naming_series', 'ACC-SINV-RET-.YYYY.-');
           frm.set_value('update_stock', 1);
       }
       else {
           frm.set_value('naming_series', 'ACC-SINV-.YYYY.-');
           frm.set_value('update_stock', 0);
       }
   }
});

Then reload (Ctrl + Shift + R) and check it.

Thank You!