How to delete field in document in firestore code example

Example: firestore javascript delete document

// define document location (Collection Name > Document Name > Collection Name >)
var docRef = Firebase.firestore().collection("Rooms").doc("bsYNIwEkjP237Ela6fUp").collection("Messages");

// delete the document
docRef.doc("lKjNIwEkjP537Ela6fhJ").delete();