two years ago I updated my Zoho CRM to the "old professional" plan because I needed invoices addons, now I don't need to use it anymore so I am planning to downgrade to the free plan.

I have two questions about it:

First: What will happens to my previous invoices (the invoices I made until now)? Will they disappear and I won't be able to see or download them anymore? 

Second: If I take a decision, how can I downgrade to free plan? If I go to  https://payments.zoho.com/html/store/mysubscription.html and try to manage my subscrition there is no way to select a downgrade from the dropdown menu. 

Thank a lot.

Veronica