Casio CZ/ VZ/ FZ - Pro Series

Is there a Casio guru out there who could help me? I've just got a VZ-10M and can't get my 
head round how to turn sounds off/on in Operation Memory mode. I just want to turn off one 
or two of the individual voices that make up a patch in Operation Memory. So, for example in 
the Oh God patch (A-1) I want to get rid of the bell sound or change it for something else.

Please help if you can. . .