No one is gonna remove the old food. Just put a notice on the frig that at the end of the day all food in the frig will be tossed and that starting today any food left in the frig will be thrown out. Maybe make it a policy that food will be tossed every Monday morning or Friday by the end of working hours. Of course things that are used by the work community (like creamer for the coffee) will be left in there but everything else will be tossed. This works if you’re working in an office that is open Monday to Friday.
What a friend of mine did to have the the old food removed from the Frigidaire fprh19d7lf office ref is he sent a memo/email out letting everyone know that due to the molded food left in the refrigerator this is the new policy for the lunchroom.