Hey there! Let's tackle your two Firebase Realtime Database deletion questions with straightforward steps and code examples that you can drop into your project right away.

Deleting a specific node boils down to targeting its exact full path and calling Firebase's built-in deletion methods. Here are examples for the most common platforms:

• Web (JavaScript)
  If your node path is something like /users/user123, you can use either remove() or set(null)—both achieve the same result:

  // Initialize database reference
  const db = firebase.database();
  // Point to the target node
  const targetNodeRef = db.ref('/users/user123');
  
  // Option 1: Use remove()
  targetNodeRef.remove()
    .then(() => console.log("Node deleted successfully!"))
    .catch(error => console.error("Deletion failed:", error));
  
  // Option 2: Use set(null) (equivalent to remove)
  targetNodeRef.set(null);
  

• Android (Kotlin)

  val db = FirebaseDatabase.getInstance()
  val targetNodeRef = db.getReference("/users/user123")
  
  targetNodeRef.removeValue().addOnCompleteListener { task ->
      if (task.isSuccessful) {
          Log.d("Firebase", "Node deleted successfully")
      } else {
          Log.e("Firebase", "Deletion failed", task.exception)
      }
  }
  

• iOS (Swift)

  let db = Database.database().reference()
  let targetNodeRef = db.child("users").child("user123")
  
  targetNodeRef.removeValue { error, ref in
      if let error = error {
          print("Deletion failed: \(error.localizedDescription)")
      } else {
          print("Node deleted successfully!")
      }
  }
  

This splits into two scenarios—depending on whether you know the target object's key (like "LAkUUug...") or need to find it via a property query.

Scenario 1: You Know the Target Object's Key #

This is the simplest case—just target the exact path to the object under "simnumbers" and delete it, same as deleting a node:

• Web Example

  const db = firebase.database();
  // Point directly to the target object in simnumbers
  const targetSimRef = db.ref('/simnumbers/LAkUUug...');
  
  targetSimRef.remove()
    .then(() => console.log("Target simnumber object deleted successfully!"))
    .catch(error => console.error("Deletion failed:", error));
  

• Android (Kotlin) Example

  val db = FirebaseDatabase.getInstance()
  val targetSimRef = db.getReference("/simnumbers/LAkUUug...")
  
  targetSimRef.removeValue().addOnSuccessListener {
      Log.d("Firebase", "Target simnumber deleted successfully")
  }.addOnFailureListener { exception ->
      Log.e("Firebase", "Deletion failed", exception)
  }
  

Scenario 2: You Don't Know the Key (Need to Query by Object Properties) #

If you only know a property of the object (like a phone number value), first query to find matching objects, then delete them by their keys:

• Web Example
  Let's say you want to delete the object where number equals "123456789":

  const db = firebase.database();
  const simNumbersRef = db.ref('/simnumbers');
  
  // Query for objects where the "number" property matches your target value
  simNumbersRef.orderByChild('number').equalTo('123456789').once('value')
    .then(snapshot => {
      // Iterate through matching results (handles multiple matches if any)
      snapshot.forEach(childSnapshot => {
          const targetKey = childSnapshot.key;
          // Delete the specific object
          simNumbersRef.child(targetKey).remove();
          console.log(`Deleted object with key: ${targetKey}`);
      });
    })
    .catch(error => console.error("Query or deletion failed:", error));
  

• Android (Kotlin) Example

  val db = FirebaseDatabase.getInstance()
  val simNumbersRef = db.getReference("/simnumbers")
  
  // Query for objects where "number" equals "123456789"
  simNumbersRef.orderByChild("number").equalTo("123456789")
      .addListenerForSingleValueEvent(object : ValueEventListener {
          override fun onDataChange(snapshot: DataSnapshot) {
              // Loop through all matching objects and delete them
              for (childSnapshot in snapshot.children) {
                  childSnapshot.ref.removeValue()
                  Log.d("Firebase", "Deleted object with key: ${childSnapshot.key}")
              }
          }
  
          override fun onCancelled(error: DatabaseError) {
              Log.e("Firebase", "Query failed", error.toException())
          }
      })
  

Quick Notes to Keep in Mind #

• Security Rules: Make sure your Firebase Security Rules allow deletion operations. For example, if you want authenticated users to delete simnumbers, your rules might look like this:

  {
    "rules": {
      "simnumbers": {
        "$key": {
          ".write": "auth != null" // Adjust based on your access requirements
        }
      }
    }
  }
  

• Batch Deletions: Realtime Database doesn't have a bulk delete API, so if your query returns multiple matches, you'll need to delete them one by one (like the examples above do).

内容的提问来源于stack exchange，提问作者ronan