Unable to downgrade from 7.2 to 7.1

Hi

I'm running into trouble with an application after upgrading to 7.2

Now i would like to downgrade this server, but can't ...

All dependencies are OK, but the command "yum history undo xx" stops with :
Error: Trying to remove "systemd", which is protected

Has anyone a tip / hint / workaround to proceed with the undo ?

Kind regards,
Norbert