It is unlikely that you’ll be able to find a temporary home for your cats while the house is on the market, and they can’t easily be removed for showings, so if there are remaining in the house you’ll need to ensure that their presence is minimized as much as possible. Clean the litter box twice daily, and completely empty and wash it at least once a week. Remove large scratch trees and all toys, ensure that food area is kept clean and tidy, and vacuum and dust daily.