How to create and update dynamic metafield in theme embedded app block in shopify public app

[Faateh]

What I am trying to do is that I have a list of webchats and that gets listed in admin panel whenever someone installs my app. Now when someone enables anyone of them , It should be seen in shopify store front. Now I checked app metafield but there is no way given to update that metafield. If someone wants to enable another webchat and disable previous webchat, that metafield should be updated. How is it possible. Kindly someone guide me.