Here's how I hacked it. Let's say I wanted to hide TOC in my index.md.

1. Add some non-standard HTML tags to the file you'd like to hide markdown from. Since these tags will not be rendered, I used them as markers. In this example, I used <hide_toc>:

   index.md

   # Hello World
   
   Here's my awesome site
   <hide_toc>

2. Create a custom javascript file with the following code:
   js/hide_toc.js

   const hasHideTocTag = !!document.querySelector("hide_toc");
   
   if (hasHideTocTag) {
     const containerRow = document.querySelector("body > .container > .row");
     const tocCol = containerRow.querySelector("& > div:first-child");
     tocCol.style.visibility = "collapse";
   }

3. Register the custom javascript file in your mkdocs.yml
mkdocs.yml

   site_name: Site
   extra_javascript:
       - js/hide_toc.js

Now for every other page you want to hide TOC, just add <hide_toc> anywhere in the file. Hope this helps