Since your site is linked to an active Premium plan, you would need to log in to your Premium dashboard and go to the Agreements section to view and modify your current agreement. The process is completely automated through the dashboard. Once the site is removed from Premium, you can proceed to remove integration.
The Google algorithm updates over the past year focused on content quality and were not related to site speed. In fact, site speed is a minor ranking factor in 2024. It's not the same issue it was years ago when mobile internet connections were slower. As you may be aware, Google has been trying to address concerns around AI and search relevance.
I understand you are correlating ads and site speed but that is not the cause of your traffic drop. Additionally, the ads on your site go through Google Ad Exchange. In other words, Google actually profits from them and would undermine its own business model if it penalized websites just for havings ads. That said, if you want to manage the ad placements and density, you can easily do so through your publisher dashboard (-> Ezoic Ads -> Ad Configuration / Ad Restrictions). If you prefer, you can also use LEAP to disable ads above the fold (-> LEAP -> Optimize -> Script Execution -> Advanced Settings).