Thank you for your question and welcome to AnxietyConnection.com.
I am not a medical professional and would not be able to give you medical advice.
You don't mention why you are looking for over-the-counter medication. Are you without insurance and unable to pay for medication? If so, most pharmaceutical companies have programs to help those without insurance.
Free or Low Cost Medications for Anxiety
As far as I know, there is no over-the-counter medication that would replace klonopin. Before taking any supplements, etc, please speak with your doctor as these can cause interactions with other medications or serious side effects.