Perhaps you love having the smell of lavender, vanilla or other aromatic fragrances in your house, but your nose is a little tired of the same scent. It's time to change the oil to something else. Before tossing the old oil for new oil, be aware that even natural oils need to be disposed of properly or they could disrupt water supplies and affect animals and vegetation. Most reed-diffuser bottles contain very small amounts of oil which can easily be disposed of safely.
Pour just a few drops of the oil down the drain to freshen up your drain. You can also pour the few drops in the toilet to freshen up the bathroom.
Soak the oil onto a paper towel. This method also only works for small amounts of oil. That small amount of oil will eventually vaporize from the paper towel.
Contact your local waste-management agency. Every state and even some cities have very specific rules on how to dispose of hazardous waste. If you have several nearly full bottles of reed-diffuser oil you need to get rid of, the local agency will give you instructions on how to dispose of it in your area. Per typical waste-management recommendations for disposing of sizable amounts of oil, mix the oil with a nonreactive material or substance such as sand and place it in a tightly sealed container.