Downgrade from Pro to Basic Plan

I have a Pro account and am wanting to downgrade my account from Pro to Basic.

I initially set up my Zoom account for my non-profit Heartland Renewable Energy Society (HRES).  The HRES board has determined to create a Zoom Account directly rather than use my account, and has now done so.  I needed to wait until our board meeting on February 3 for a final Zoom account strategy. This was after my annual billing date for my personal Zoom account of 1/23/2022. 

So, I need to downgrade my personal account from Pro to Basic.  I would like to pay the monthly Pro fee for one month and then go to a Basic plan following that.  However, I am locked out of making any changes to my personal account while an accounts payable balance exists.  Please let me know how to proceed.