I want to remove a dishwasher in Laguna Niguel, Ca and then order one... SOmeone told me I am not allowed to take the dishwasher out until I have another to replace it?? Is this a code?

Don't know about the code, but the appliance store where you purchase your new one may take the old one for a small fee, when they deliver the new dishwasher. You might ask. That saves the disposal.

That sounds absurd to me. All you have to do is cap off any open drain or vent with the right fitting so that sewer gasses and waste can't back up.