You can downgrade to a different, currently available plan at any time. The option is not available in the dashboard, but you can contact us through the chat icon in the bottom right corner and we would be happy to assist you. If you're downgrading, the price difference for the remainder of your billing cycle will be applied as credit in the next billing cycle. If you want to downgrade to a free plan, this would be treated as a cancellation, so you can follow the steps in the question above this one.
If you wish to downgrade your plan, you need to first ensure that your workspace falls within the limits of your new plan.