@Khosla, Devesh - (khosla) thanks for the question. based on this similar Stack Overflow thread you can view and delete APNS registrations in Azure portal by using Server Explorer in Visual Studio.
Here are the steps:
- Connect to Azure from Server Explorer
- Find Notification Hub section
- Select your hub
- On the right side, you will see two tabs: Test Send and Device Registration
- On Device Registration tab, you will see a list of registrations. You can edit or delete them.
Alternatively, you can also send a test broadcast message from Azure portal and see the subscribers in the Result area
Hope that helps.