delete method
Implementation
@override
Future<StudySubject> delete() async {
await deleteProgress();
final response = await env.client.from(tableName).delete().eq('id', id).single().execute();
SupabaseQuery.catchPostgrestError(response);
final json = response.data as Map<String, dynamic>;
json['study'] = study.toJson();
return StudySubject.fromJson(json);
}