If there is need to make some changes to an Airbnb Listing which is currently synced to a ResBook Stock Unit, go to Airbnb > Listings > ResBook sync > Click on ... > Stop sync. Step 2 is to go to ResBook > Settings > Portals > Airbnb and verify that the Listing ID has disapeared  the Listing ID column. Once done, proceed with the changes on Airbnb and resync the Stock unit with the Listing.