How do I downgrade to an older point release of CentOS 7.x
I recently upgraded my server to CentOS 7.5 but, after the upgrade, I'm running into issues. Is it possible to downgrade back to CentOS 7.4?
Possible, maybe. Recommended, no. When a new CentOS 7.x is released, the older version is effectively EOL. For example, no patches will be released for 7.4 because 7.5 is the patched version.
What sort of issues are you running into? Are they related to a performance slow-down or broken software? The best solution would be to work towards a fix instead of downgrading your system to a less secure os version.
Redhat has a great article on downgrading to a previous minor version:
How to downgrade kernel and redhat-release to a previous minor version of Red Hat Enterprise Linux
Essentially, the command you need to run is
yum downgrade redhat-release where redhat-release is the release version of the CentOS you'd like to downgrade to.
Here's a great article on serverfault discussing the negatives of downgrading.