Your APK won't be uploaded to the Google Play Developer Console if its package name is the same as another app that already exists in the Google Play Store. To give it a unique name, we'll first open Android Studio and import the Android folder of our app to it.
Select Import Project (Eclipse ADT, Gradle, etc.) from the Android Studio welcome screen. Then navigate to the repository for your project and import just the Android folder within.
Afterwards, open AndroidManifest.xml and change the package name on the second line.
Then, right-click on your app folder that contains the package identifier, and select Refactor | Rename. Then, give your package a new name:
Now open up build.gradle within the android/app ...