When we create a Functions app in Azure and access the URL, it takes us to the nice home page (Your Functions app up and running).
Fig 1 : Functions App - Get URL from Overview
Fig 2 : Functions App - Home page
If you don't want to show the home page, just add AzureWebJobsDisableHomepage=true to your function app application settings. In order to add Application settings, navigate to Functions App > Left menu > Settings > Configuration > Application settings > add new application setting. > Save.
Fig 3 : Functions App - Add application setting
Now if you access the function URL, it will not show the home page.
To get back your home page, delete AzureWebJobsDisableHomepage setting from your application settings.