Are you using the built-in provider you must disable the feature in the UI at the parent level. All children will be affected.

Read more at https://docs.developers.optimizely.com/content-management-system/docs/optimizely-languages#configure-auto-translation

If you want a more granular approach you'll need to do some coding.

Ive looked at the plugin, and its really half done, not every thing is implemented the right way. I will report that.There is  

"EPiServer": {
    "CmsUI": {
      "LanguageManager": {
        "RestrictedTypes": [
          "AlloySandbox.Models.Pages.*",
          "AlloyTemplates.Models.Pages.ExamplePage2"
        ]
      }
    },

But it is never used in the code! So the way is to override LanguageBranchManager.

You can exlude properties by overriding IEnumerable<string> ExcludedProperties => new string[2] { "CatalogContent.SeoUri", ".MetaTitle" };

But you need to override many methods in the ILanguageBranchManager because it is poorly build. 

Still, i dont see you can disable the button, you can trigger the autotranslate but return false, you get a message "Error see the logs" which is not user friendly.