What is the proper way to downgrade from 7.3 to 7.2 ?

Please refer instead to the Knowledge Solution How to use yum to downgrade or rollback some package updates?.
Note the guidances that package downgrades can be troublesome due to rpm package scriptlets being unreversable. Please ensure backups have been created for recovering should problems arise.

Hi:
I was trying to downgrade RHEL server from 7.3 to 7.2 by yum history undo, but I've hit an error :

$ yum history undo 69
...
Updated zlib-1.2.7-15.el7.x86_64 @rhel-7-server-rpms
Update 1.2.7-17.el7.x86_64 @rhel-7-server-rpms
Updated zlib-devel-1.2.7-15.el7.x86_64 @rhel-7-server-rpms
Update 1.2.7-17.el7.x86_64 @rhel-7-server-rpms
Failed to downgrade: epel-release-7-8.noarch
Failed to downgrade: ioping-0.9-1.el7.x86_64
Error: No package(s) available to install

What is the proper way to downgrade my system?

Regards,
Joao