How to remove child nodes in firebase android?
If you are using DatabaseReference for firebase
DatabaseReference dbNode = FirebaseDatabase.getInstance().getReference().getRoot().child("Node");
Here Node represents the child which you wish to delete
dbNode.setValue(null);
If you are using a dataSnapshot
i.e., while you are working on some data change events
dataSnapshot.getRef().setValue(null);
To remove data:
firebase.child(id).removeValue();
You might do well to have a look at the Firebase documentation for Android btw, which covers this and many more topics.