code: public int delete(String table, String whereClause, String[] whereArgs) {
          acquireReference();
          try {
              SQLiteStatement statement =  new SQLiteStatement(this, "DELETE FROM " + table +
                      (!TextUtils.isEmpty(whereClause) ? " WHERE " + whereClause : ""), whereArgs);
              try {
                  return statement.executeUpdateDelete();
              } finally {
                  statement.close();
              }
          } finally {
              releaseReference();
          }
      }
docs: Convenience method for deleting rows in the database.
  
  @param table the table to delete from
  @param whereClause the optional WHERE clause to apply when deleting.
  Passing null will delete all rows.
  @param whereArgs You may include ?s in the where clause, which
  will be replaced by the values from whereArgs. The values
  will be bound as Strings.
  @return the number of rows affected if a whereClause is passed in, 0
  otherwise. To remove all rows and get a count pass "1" as the
  whereClause.