@FXML
    private void DeleteButtonAction(ActionEvent event) throws IOException {
      //alterar conection!
      String myDriver = "org.gjt.mm.mysql.Driver";
      String myUrl = "jdbc:mysql://localhost/test";
      Class.forName(myDriver);
      Connection conn = DriverManager.getConnection(myUrl, "root", "");
        
      //alterar table name 
        String SQL = "DELETE FROM department WHERE dept_no = ? ";
        PreparedStatement pstmt = null;

// get a connection and then in your try catch for executing your delete...

        pstmt = con.prepareStatement(SQL); 
        pstmt.setString(1, Integer.parseInt(textfield.getText()));
        pstmt.executeUpdate();
      
      conn.close();
    }