Hi,

I think it's doable. Just create dropdown list (using menu/data/validation) near each item and add an IF function to the function that uses the items as an arguent. Something like this 
=IF(A1="Enabled" , function(...your function with item included here...) , function (...your function with item excluded...))
In the example A1 is where the dropdown list of enabled/disabled is located.
Can you upload the worksheet here? It would be a lot easier to work with.