I have same issue but you can’t downgrade to free selling, eBay system  is forcing this, only allowing upgrades with monthly payment subscriptions, even though their email says that you can cancel it if you want to. 
The biggest issue is they are removing use of APIs under free and Pro accounts, forcing sellers to buy move to Pro Basic for $27.45 a month. After 25 years Im ready to leave, they couldn’t care less about their loyal sellers and only care about attracting new business.