private void buttonRemove_Click(object sender, RoutedEventArgs e)
 {
     try
     {
         if (textBoxWord.Text.Length > 0 && textBoxCategory.Text.Length > 0)
         {
             if (classifier.DeleteFeatureCategoryCombination(textBoxWord.Text, textBoxCategory.Text))
             {
                 MessageBox.Show("Successfull removed from data base!");
                 showlog();
             }
             else
             {
                 MessageBox.Show("Such combination don't exist!");
             }
         }
     }
     catch (Exception ex)
     {
         MessageBox.Show(ex.Message);
     }
 }