Visual Integrator Importing (and removing) Paperless Office for Contacts

I set up a VI job to set paperless office settings for all of our customers so it would email their A/R Statement to a contact code (rather than the customer email). Now I'm trying to figure out how I can remove that contact code using a similar job (made a mistake and want to fix then change it). Is there something I can put in the L.ToContactCode field in my CSV, or set on the import field properties for that data field so that it will remove a contact code? I don't have a lot of experience here, so any help and a detailed explanation would be greatly appreciated. Or if there is a way to modify the contact code that is already there and replace with a different one. If I try to import again with the correct contact code, it just adds the new one and does not change the previous one.