def remove_index(columns, index_name = nil)
      options = if index_name
                  { name: index_name }
                else
                  { column: columns }
                end
      migration.remove_index(table_name, options)
    end
def remove_index(columns, index_name = nil)
      options = if index_name
                  { name: index_name }
                else
                  { column: columns }
                end
      migration.remove_index(table_name, options)
    end
Removes the index in the given columns or by its name

 @param columns [Array<String>, Array<Symbol>, String, Symbol]
 @param index_name [String]