Roll back to the prior version

[Mintra]

Hello,

From the previous post, I've asked for the updates from v.4.1 to 4.2.
To be through before the upgrade, if the WebEx portal corrupts after the update(4.2), what is the best practice for rolling back to the old version(4.1)?
Do I copy and paste the backup folder(backup 4.1) into the existing installation folder(4.2) or do I need to use the old installer(4.1) to roll back?

Which area do I need to check to ensure the update works as expected?

Thanks!
Mintra