Removing Dealer Install Options

[HummerNewbie]

I know this has been discussed before and I did a search but couldn't find the info. Are the dealer installed options such as side steps tied to the vehicle on their invoice? I know they are shipped to the dealer then added there but. Basically what I am asking is if they have a unit on the lot that has an option like the side steps and they are on the window sticker, they should be able to remove and deduct the price right? In a brief discussion a salesman (mine wasn't there) told me they couldn't. I don't think this is true but wanted to double check. Don't see why that can't just remove the option, deduct the price and add it to another vehicle on the lot. Also, has anyone installed the Terk XM adaptor to a Monsoon or other H3 system? Thanks for any info.