Hi,
Based on the debug data, I can see that HikaShop is not even called on that page.
That's really strange.
There are two methods to unpublish an email:
-using the toggle on the listing of emails
-editing the email by clicking on its name and turning off the published setting there and saving.
Please try both methods. One of them should definitely work (both work on our end so I'm assuming it either come from a security extension on your website or some security setting of your PHP/Apache blocking the parameters or something).