title: Delete collection firestore:go
body: <p>I took a data set of 10 collections from api xyz, then updated it to firebase for the first time. </p>
  
  <p>On the second update, api xyz has 9 collections available, How to make the 2nd update with only 9 collections (the existing ones being overwritten and the extra collections from the first update should be deleted)?</p>
  
  <p>I used to delete all the collections and then update but that method is not appropriate.</p>