Hello x123, this is your business so you can do what you want. There are many work places that do not allow staff to wear strong smells. You could use the 'health and safety' issue if you feel you need to give a reason. For example, smells contaminating food or it could cause someone to have an asthma attack etc. Or you could come up with a compromise and just ask if she could wear a perfume that is less stinky!