Vault cannot be deleted as there are existing resources within the vault

I spent almost half of a day to figure out this issue.  Exception was self explanatory but finding the solution was difficult.

You may experience this error when try to remove a Recovery service vault, Root cause is explained below.

This error signifies that Recovery vault has dependency on a storage account. To resolve this issue, you have to unregister storage account from vault.

Steps are very easy :-

1. Go to target recovery service vault 

2. Select "Backup Infrastructure" from left side panel

3. Select "Storage Accounts" from left side panel

4. From the right side panel , select the storage name and then click on "Unregister"

Now try to delete the vault again and see the magic.