Downgrade procedures for downgrading all Oracle Grid Infrastructure cluster types to 12c Release 2 (12.2) after successful or failed upgrade.

• Downgrading Oracle Standalone Cluster to 12c Release 2 (12.2)
  Use this procedure to downgrade Oracle Standalone Cluster to Oracle Grid Infrastructure 12c Release 2 (12.2) after a successful upgrade.
• Downgrading Oracle Grid Infrastructure to 12c Release 2 (12.2) when Upgrade Fails
  If upgrade of Oracle Grid Infrastructure fails before CVU post upgrade checks succeed, then you can run setup.exe and downgrade Oracle Grid Infrastructure to the earlier release.