code: @CheckResult protected Observable<Integer> delete(@NonNull final String table,
        @Nullable final String whereClause, @Nullable final String... whereArgs) {
      return Observable.defer(new Func0<Observable<Integer>>() {
        @Override
        public Observable<Integer> call() {
          return Observable.just(db.delete(table, whereClause, whereArgs));
        }
      });
    }
docs: Delete data from a table
  
  @param table The table name
  @param whereClause the where clause
  @param whereArgs the where clause arguments
  @return <b>deferred</b> Observable with the number of deleted rows