You want to roll back from a successfully installed Symantec Endpoint Security [SES] agent version to an earlier one (i.e. from 14.3 RU7 to 14.3 RU6)
Endpoint Security Console /ICDm
Unfortunately there is no feature available in SES to roll back from a successfully installed agent version to a previous one.
The only feasible way to downgrade the version of the agent is to uninstall the current version and install the desired one.