How to remove 12.1.1 on 2012 R2?

I got a problem with SEP 12.1.1

Unfortunatelly one of my customers installed the SEP Client on a Windows Server 2012 R2

It’s not possible to launch the gui (compatibility issue)

It’s not possible to uninstall SEP via control panel

I tried to manually remove SEP like described in http://www.symantec.com/business/support/index?pag...

But since the tamper mode is activated, it is not possible to change the registry or msconfig settings.

I also tried to update it to version 12.1.5 although the setup runs fine nothing seems to change. The control panel still shows 12.1.1 as the installed version

Is there any way I can uninstall the SEP client?

Thanks in advance