private void DeleteButton_Click(object sender, RoutedEventArgs e) { Tag tag = (Tag)dataGridtag.SelectedItem; TagDataService tagDataService = new TagDataService(new EntityFramework.TimetableManagerDbContext()); tagDataService.DeleteTag(tag.TagId).ContinueWith(result => { MessageBox.Show("Deleted"); }); _ = TagDataList.Remove(tag); }