removeChild() via class file

Hi,

i have a problem to delete text field via class file.

Im getting this error

ArgumentError: Error #2025: The supplied DisplayObject must be a child of the caller.           at flash.display::DisplayObjectContainer/removeChild()           at dzn::DeleteTextField/deleteTF()

Can somebody help me with that?

Here is my Main.as

package  
{
     import flash.display.Sprite;
     import flash.display.*;
     import flash.events.MouseEvent;
     import flash.text.TextField;
     import flash.text.TextFormat;
  
     import dzn.InputTextField;
     import dzn.DeleteTextField;
     public class Main extends Sprite 
     {
         public var ITF:InputTextField = new InputTextField;
         public var DTF:DeleteTextField = new DeleteTextField();   
         public function Main() 
         {
                   // There is 2 static button on the stage "loginBtn" and "hideTf". 
                    loginBtn.addEventListener(MouseEvent.CLICK, initKeyboard); // Display InputTextField            
                hideTf.addEventListener(MouseEvent.CLICK, hideTFF); // Delete InputTextField - This is working  
                    hideTf.addEventListener(MouseEvent.CLICK, DTF.deleteTF); // Call deleteTF function via class DeleteTextField to delete InputTextField - This is not working
                    // If I call deleteTF function in DeleteTextField class, then i can access function but i can't delete Text Field
         }
         
         public function initKeyboard(e:MouseEvent):void 
         {
                    // When button is clicked then it creating new Input text field 
                    ITF = new InputTextField(); 
                    addChild(ITF);
         }
  
         public function hideTFF(e:MouseEvent):void
         {
                    // When clicked then it removing Input text field
                    this.removeChild(ITF);
         }
     }
}

Here is my InputTextField.as

package dzn 
{
          import flash.display.Sprite;
          import flash.events.MouseEvent;
          import flash.text.TextField;
          import flash.text.TextFormat;
  
          public class InputTextField extends Sprite 
          {
                    public var txt:TextField = new TextField();
  
                    public function InputTextField() 
                    {
                              txt.width = 1160;
                              txt.height = 350;
                              txt.background = true;
                              txt.backgroundColor = 0xffffff;
                              txt.border = true;
                              txt.borderColor = 0xcccccc;
                              txt.multiline = true;
                              txt.wordWrap = true;
  
                              txt.defaultTextFormat = new TextFormat("Arial", 25, 0x546770,true,null,null,null,null,"left");
                              txt.text = "PRESS HERE"
                              addChild(txt);
                              txt.x = 20;
                              txt.y = 84;
                    }
          }
}

Here is my DeleteTextField.as

package dzn
{
          import flash.display.Sprite;
          import flash.display.*;
          import flash.events.MouseEvent;
          import flash.text.TextField;
          import flash.text.TextFormat;
  
          import dzn.InputTextField;
  
          public class DeleteTextField extends Sprite 
          {
               public var ITF:InputTextField;
  
               public function DeleteTextField() {
                         ITF = new InputTextField();
               }
  
               public function deleteTF(e:MouseEvent):void
               {
                         this.removeChild(ITF); // This is not working
               }
          }
}