Yes. If you don't want to be charged a monthly subscription fee, you can downgrade your account from the Professional plan to the Individual plan from the My Services page
in Seller Central (log-in required).
If you downgrade, your account remains open and you can continue to sell products on Amazon as an Individual selling partner, but you will lose access to Professional plan benefits, such as bulk product uploads, order reports, selling partner-customised shipping fees and special listing features. Please also keep in mind that only offers from Professional selling partners are eligible for featured offer status on product detail pages.