android - Firebase Delete -

i have 1 listview , adapter imagebutton delete data, don't know how delete data setonclick. need click imagebutton , delete data. have data type room not null.

    public class orgmanageroom extends appcompatactivity {              private listview listview;             private arrayadapter<string> arrayadapter;             private arraylist<string> list_of_rooms = new arraylist<>();         arraylist<hashmap<string, string>> myarrlist;         public arraylist<string> arr;         public arrayadapter adapter;          private databasereference mdatabase = firebasedatabase.getinstance().getreference().getroot();            @override         protected void oncreate(bundle savedinstancestate) {             super.oncreate(savedinstancestate);             setcontentview(r.layout.activity_org_manage_room);      //        listview = (listview)findviewbyid(r.id.listview);     //        listview.setadapter(new imageadapter(this));     //        arrayadapter = new arrayadapter<string>(this,android.r.layout.simple_list_item_1,list_of_rooms);     //        listview.setadapter(arrayadapter);             createadapter();               listview.setonitemclicklistener(new adapterview.onitemclicklistener() {                 @override                 public void onitemclick(adapterview<?> parent, view view, int position, long id) {                      intent = new intent(orgmanageroom.this,orgadduser.class);                     startactivity(i);                  }             });           }          private void createadapter() {             listview = (listview)findviewbyid(r.id.listview);             listview.setadapter(new imageadapter(this));             mdatabase = firebasedatabase.getinstance().getreference().child("allroom");              mdatabase.addvalueeventlistener(new valueeventlistener() {                 @override                 public void ondatachange(datasnapshot datasnapshot) {                      set<string> set = new hashset<string>();                     iterator = datasnapshot.getchildren().iterator();                      while (i.hasnext()){                          set.add(((datasnapshot)i.next()).getkey());                      }                      list_of_rooms.clear();                     list_of_rooms.addall(set);      //                arrayadapter.notifydatasetchanged();                  }                  @override                 public void oncancelled(databaseerror databaseerror) {                  }             });         }           public class imageadapter extends baseadapter {             private context context;              public imageadapter(context c) {                 // todo auto-generated method stub                 context = c;             }              public int getcount() {                 // todo auto-generated method stub                 return list_of_rooms.size();             }              public object getitem(int position) {                 // todo auto-generated method stub                 return position;             }              public long getitemid(int position) {                 // todo auto-generated method stub                 return position;             }              public view getview(final int position, view convertview, viewgroup parent) {                 // todo auto-generated method stub                  layoutinflater inflater = (layoutinflater) context                         .getsystemservice(context.layout_inflater_service);                  if (convertview == null) {                     convertview = inflater.inflate(r.layout.deleteroom, null);                 }                  // colimgid                 textview txtposition = (textview) convertview.findviewbyid(r.id.colimgdesc);                 txtposition.setpadding(10, 0, 0, 0);                 txtposition.settext(list_of_rooms.get(position));                  imagebutton cmdshared = (imagebutton) convertview.findviewbyid(r.id.imgcmdshared);                 cmdshared.setonclicklistener(new view.onclicklistener() {                     public void onclick(view v) {                         toast.maketext(orgmanageroom.this, "test" + list_of_rooms.get(position), toast.length_long).show();                      }                 });                  return convertview;              }          }     } 

sorry, edit code , make project chat firebase , show listview listroom add user , delete user , manageroom. deletes room edit nameroom. same need click imagebutton delete listroom.