Hello and welcome to health care magic forum,
The bad smell is due to the plaque
and food debris which got accumulated in your denture.
Your denture has to be cleaned properly,both inner as well as outer surfaces using toothbrush and toothpaste.
please make sure that you clean your denture daily in the same way as you brush your teeth.
Rinse your denture after every meals.
Whenever you are not wearing denture,please put them in a bowl of cold
Also clean and floss your tongue daily.
I wish you good health.