Uninstall Document for SQL 2008 R2 SP2 Service Pack in a Active - Active Clustered Environment

Are there "how to" documents on how to uninstall SQL 2008 R2 SP2 back to SQL 2008 R2 in a Windows-SQL Clustered enviroment.  My objective is to put together a detailed Rollback Plan in the event the SP2 needs to be uninstalled.

Thanks,