def remove_index(columns, index_name = nil)
      columns = [columns].flatten.map(&:to_sym)
      from_origin = @origin.indices.find { |_, cols| cols.map(&:to_sym) == columns }
      index_name ||= from_origin[0] unless from_origin.nil?
      index_name ||= idx_name(@origin.name, columns)
      ddl('drop index `%s` on `%s`' % [index_name, @name])
    end
def remove_index(columns, index_name = nil)
      columns = [columns].flatten.map(&:to_sym)
      from_origin = @origin.indices.find { |_, cols| cols.map(&:to_sym) == columns }
      index_name ||= from_origin[0] unless from_origin.nil?
      index_name ||= idx_name(@origin.name, columns)
      ddl('drop index `%s` on `%s`' % [index_name, @name])
    end
Remove an index from a table

 @example

   Lhm.change_table(:users) do |m|
     m.remove_index(:comment)
     m.remove_index([:username, :created_at])
   end

 @param [String, Symbol, Array<String, Symbol>] columns
   A column name given as String or Symbol. An Array of Strings or Symbols
   for compound indexes.
 @param [String, Symbol] index_name
   Optional name of the index to be removed