One account should be deleted before linking two existing ones

I'm trying to replicate the example of merging two existing accounts, but I think that the problem is that the docs doesn't explicit says that the prevUser needs to be deleted from Firebase Auth, and not only its data from my "repo", it just says that I need to delete the users's data:

snippets-web/snippets/auth-next/link-multiple-accounts/auth_merge_accounts.js

Lines 21 to 22 in 88aa8eb

    
           // Delete the user's data now, we will restore it if the merge fails 
        
           repo.delete(prevUser);

And it says that it would be restored if necessary, but it doesn't restore the actual user that should be deleted beforehand. But to restore it we would need the prevUser credential, that wouldn't be valid anymore?! Idk...

	// Delete the user's data now, we will restore it if the merge fails
	repo.delete(prevUser);