If you upgrade from older CM version save the old license key

If you upgrade from CM6.50 or older and you want to remove the old CM installation go on with
5.1 Uninstall old CM Installation

If you want to change from 32bit to 64bit CM installation you have to go through the additional steps of 5.2 Oracle client uninstall

If there are any other situations you might have in your environment please get in contact with support team before starting any upgrade actions