[Vuejs]-How to limit a certain page only for admin access with vue?

You need to do the enforcement on the backend, not the frontend, otherwise users would be able to (easily) circumvent it.

What you need to do is add access rules to the Firebase database (realtime db or firestore or cloud storage, whichever you’re using).

Here’s a link to get you started: https://firebase.google.com/docs/rules