Answers for "how to delete a doc from collection in firebase real-time database"

how to delete document firestore database

db.collection("cities").doc("DC").delete().then(() => {
    console.log("Document successfully deleted!");
}).catch((error) => {
    console.error("Error removing document: ", error);
});

how to delete firebase collection

this.db
  .collection('cart')
  .get()
  .toPromise()
  .then((querySnapshot) => {
  querySnapshot.forEach((doc) => {
    doc.ref.delete();
  });
});